Compounds and uses thereof

ABSTRACT

A pharmaceutical composition is described herein, including an antimicrobial agent and a compound having Formula A, or Formula B. Methods of using the pharmaceutical compositions to treat microbial infection are also described.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent Application No. 62/770,359, filed on Nov. 21, 2018, the contents of which is hereby incorporated by reference in its entirety.

INCORPORATION BY REFERENCE

All patents, patent applications, and publications cited herein are hereby incorporated by reference in their entirety in order to more fully describe the state of the art as known to those skilled therein as of the date of the invention described herein.

FIELD OF THE INVENTION

This invention generally relates to compounds and pharmaceutical compositions.

BACKGROUND

There is a need to develop new antibiotics but also to develop new strategies to deal with antibiotic resistance. The problem with antibiotic therapy is that bacteria and other microorganisms will, given time, evolve to become resistant. Large pharmaceutical companies have mostly abandoned antibiotic development because it is both expensive and the investment returns are not as large as those of other chronic illnesses.

Antibiotic adjuvants, also termed “resistance breakers” or “antibiotic potentiators,” when co-administered with an antibiotic either block the resistance mechanism of the bacteria or enhance the action of the antibiotic drug. The main antibiotic adjuvants currently marketed are the inhibitors of β-lactamase enzymes produced by drug resistant bacteria to break down β-lactam antibiotics, such as the penicillins. However, there are other resistance mechanisms for β-lactams and other classes of antibiotics for which these adjuvants would have no effect. It seems, then, that even though the idea of antibiotic adjuvants is promising, only a very limited number of these compounds have progressed to clinical applications.

Adjuvants offer an advantage in current antimicrobial therapies as they can either enhance the activity of antibiotics or reduce/block resistance of the pathogen. Antibiotic adjuvants have been broadly classed into three categories: 1A, 1B, and 2. Category 1A adjuvants directly inhibit antibiotic resistance by inactivating enzymes, efflux pump systems, or alternate targets while category 1B adjuvants enhance antibiotic activity by circumventing intrinsic resistance mechanisms, including metabolic pathways or physiology other than direct inhibition of specific resistance elements. Category 2 adjuvants do not directly impact bacteria but rather operate on host properties to potentiate antibiotic action.

SUMMARY

A novel approach for developing antimicrobial agents is to search for new antimicrobial agents and make established antibiotics useful again. One way in which existing antimicrobial agents can become effective against drug resistant pathogens is to develop potentiators that potentiate the antibiotics. Described herein are antimicrobial agents and compounds that potentiate existing antimicrobial agents.

In one aspect, a pharmaceutical composition is disclosed, including an antimicrobial agent and a compound having Formula A or B,

where

each occurrence of R₉ is independently selected from the group consisting of NH₂, NO₂, OH, CHO, halogen, and C₁ to C₆ alkyl optionally substituted with one or more of halogen, OH, NH₂, NO₂, or CHO; and where R₉ is substituted on the phenyl ring of Formula A or the imidazole ring of Formula B;

m is 0 to 5;

each occurrence of R₁₀ is independently H, halogen, OH, CN, NO₂, OCF₃, (C₁ to C₆) alkyl, (C₂ to C₆)alkenyl, (C₂ to C₆)alkynyl, (C₁ to C₆)alkoxy, (C₃ to C₇)cycloalkyl, 3-7-membered heterocycle, (C₁ to C₆)alkylthio, NR_(a)R_(b), (C₁ to C₆)haloalkyl, (CH₂)_(p)(C₃ to C₇)cycloalkyl, (CH₂)_(p)OR_(a), (CH₂)_(p)SR_(a), (CH₂)_(p)NR_(a)R_(b), (CH₂)_(p)(C₁ to C₆)haloalkyl, or CH(indole)₂, in which said heterocycle includes at least one heteroatom selected from the group consisting of nitrogen, oxygen and sulfur and may be optionally substituted by from one to three groups which may be the same or different selected from the group consisting of halogen, OH, CN, (C₁ to C₄)alkyl, (C₁ to C₄)haloalkyl and (C₁ to C₄)alkoxy, or alternatively two R₁₀ taken together with the ring atoms they are connected to form a 3-7-membered aromatic ring; where R₁₀ is a group substituted on the indole ring and/or the phenyl ring of Formula A or on the indole ring and/or the imidazole ring of Formula B;

each of n, o, p and q is independently an integer from 0 to 4;

R₇ and R₈ are each independently H, halogen, OH, CN, OCF₃, (C₁ to C₆)alkyl, (C₂ to C₆)alkenyl, (C₂ to C₆)alkynyl, (C₁ to C₆)alkoxy, (C₃ to C₇)cycloalkyl, 3-7-membered heterocycle, (C₁ to C₆)alkylthio, NR_(a)R_(b), (C₁ to C₆)haloalkyl, (CH₂)_(p)(C₃ to C₇)cycloalkyl, (CH₂)_(p)OR_(a), (CH₂)_(p)SR_(a), (CH₂)_(p)NR_(a)R_(b), or (CH₂)_(p)(C₁ to C₆)haloalkyl, in which said heterocycle contains at least one heteroatom selected from the group consisting of nitrogen, oxygen, and sulfur and may be optionally substituted by from one to three groups which may be the same or different selected from the group consisting of halogen, OH, CN, (C₁ to C₄)alkyl, (C₁ to C₄)haloalkyl, and (C₁ to C₄)alkoxy;

each occurrence of R₁₁ is independently H, halogen, OH, CN, NO₂, OCF₃, (C₁ to C₆) alkyl, (C₂ to C₆)alkenyl, (C₂ to C₆)alkynyl, (C₁ to C₆)alkoxy, (C₃ to C₇)cycloalkyl, 3-7-membered heterocycle, (C₁ to C₆)alkylthio, NR_(a)R_(b), (C₁ to C₆)haloalkyl, (CH₂)_(p)(C₃ to C₇)cycloalkyl, (CH₂)_(p)OR_(a), (CH₂)_(p)SR_(a), or (CH₂)_(p)NR_(a)R_(b), in which said heterocycle includes at least one heteroatom selected from the group consisting of nitrogen, oxygen and sulfur and may be optionally substituted by from one to three groups which may be the same or different selected from the group consisting of halogen, OH, CN, (C₁ to C₄)alkyl, (C₁ to C₄)haloalkyl and (C₁ to C₄)alkoxy;

R_(a) and R_(b) are each independently H, (C₁ to C₆)alkyl, (C₂ to C₆)alkenyl, or (C₃ to C₇)cycloalkyl; and

x is absent; or alternatively x is a positive charge and R₁₁ is absent.

In any one of the embodiments described herein, R₇ and R₈ are each independently H, halogen, OH, CN, OCF₃, (C₁ to C₆)alkyl, (C₂ to C₆)alkenyl, (C₂ to C₆)alkynyl, (C₁ to C₆)alkoxy, or (C₃ to C₇)cycloalkyl.

In any one of the embodiments described herein, R₇ and R₈ are each independently (C₁ to C₆)alkylthio, NR_(a)R_(b), (C₁ to C₆)haloalkyl, (CH₂)_(p)(C₃ to C₇)cycloalkyl, (CH₂)_(p)OR_(a), (CH₂)_(p)SR_(a), (CH₂)_(p)NR_(a)R_(b), or (CH₂)_(p)(C₁ to C₆)haloalkyl.

In any one of the embodiments described herein, R₇ and R₈ are each independently 3 to 7-membered heterocycle optionally substituted by from one to three groups which may be the same or different selected from the group consisting of halogen, OH, CN, (C₁ to C₄)alkyl, (C₁ to C₄)haloalkyl, and (C₁ to C₄)alkoxy.

In any one of the embodiments described herein, R₇ and R₈ are each independently OCH₃ or (C₁ to C₆)alkoxy.

In any one of the embodiments described herein, R₇ and R₈ are each independently H, (C₁ to C₆)alkyl, NH₂, Br, or OH.

In any one of the embodiments described herein, R₁₁ is H, halogen, OH, or (C₁ to C₆) alkyl.

In any one of the embodiments described herein, the compound has the structure of Formula A′:

In any one of the embodiments described herein, at least one R₉ is selected from the group consisting of NH₂, OH, CHO, halogen, and (C₁ to C₆)alkyl substituted with one or more halogen, NH₂, CHO, or OH.

In any one of the embodiments described herein, R₉ is independently selected from the group consisting of halogen, CH₃, OH, NH₂, NO₂, CHO, and C(CH₃)₃.

In any one of the embodiments described herein, at least one R₉ is halogen.

In any one of the embodiments described herein, at least one R₉ is F, Cl, or Br.

In any one of the embodiments described herein, at least one R₉ is NH₂ or (C₁ to C₆)alkyl substituted with one or more NH₂.

In any one of the embodiments described herein, at least one R₉ is CHO or (C₁ to C₆)alkyl substituted with one or more CHO.

In any one of the embodiments described herein, at least one R₉ is OH or (C₁ to C₆)alkyl substituted with one or more OH.

In any one of the embodiments described herein, each occurrence of R₁₀ is independently H, halogen, OH, CN, OCF₃, (C₁ to C₆)alkyl, (C₂ to C₆)alkenyl, (C₂ to C₆)alkynyl, (C₁ to C₆)alkoxy, or (C₃ to C₇)cycloalkyl.

In any one of the embodiments described herein, each occurrence of R₁₀ is independently 3-7-membered heterocycle, (C₁ to C₆)alkylthio, NR_(a)R_(b), (C₁ to C₆)haloalkyl, (CH₂)_(p)(C₃ to C₇)cycloalkyl, (CH₂)_(p)OR_(a), (CH₂)_(p)SR_(a), (CH₂)_(p)NR_(a)R_(b), or (CH₂)_(p)(C₁ to C₆)haloalkyl.

In any one of the embodiments described herein, R₁₀ is independently selected from the group consisting of halogen, CH₃, N(CH₃)₂, NO₂, CHO, OH, OCH₃, NH₂, C(CH₃)₃, and

or where two R₁₀ taken together form a 6-membered aromatic ring.

In any one of the embodiments described herein, o and q are each independently 0, 1, or 2.

In any one of the embodiments described herein, o and q are 0.

In any one of the embodiments described herein, m is 1, 2, or 3.

In any one of the embodiments described herein, n is 1 or 2.

In any one of the embodiments described herein, n is 3 or 4.

In any one of the embodiments described herein, n is 0.

In any one of the embodiments described herein, the compound is selected from the compounds in Table 1 or Table 2.

In any one of the embodiments described herein, the compound is

In any one of the embodiments described herein, the compound is

In any one of the embodiments described herein, the antimicrobial agent is an antibacterial agent.

In any one of the embodiments described herein, the antimicrobial agent is an antifungal agent.

In any one of the embodiments described herein, the antimicrobial agent is a macrolide, a folic acid synthesis inhibitor, a fluoroquinolone, an aminoglycoside, a monobactam, a cephalosporin, a glycopeptide, a β-lactam, a carbapenem, or a tetracycline.

In any one of the embodiments described herein, the antimicrobial agent is selected from the group consisting of ampicillin, imipenem, cephalexin, erythromycin, aztreonam, trimethoprim, streptomycin, ciprofloxacin, vancomycin, doxycycline, chloramphenicol, and kanamycin.

In any one of the embodiments described herein, the compound is

and the antimicrobial agent is selected from the group consisting of ampicillin, imipenem, cephalexin, erythromycin, streptomycin, vancomycin, doxycycline, and kanamycin.

In any one of the embodiments described herein, the compound is

and the antimicrobial agent is selected from the group consisting of ampicillin, imipenem, cephalexin, aztreonam, trimethoprim, streptomycin, ciprofloxacin, vancomycin, doxycycline, and kanamycin.

In any one of the embodiments described herein, the compound is

and the antimicrobial agent is selected from the group consisting of ampicillin, imipenem, cephalexin, erythromycin, aztreonam, trimethoprim, streptomycin, ciprofloxacin, vancomycin, doxycycline, chloramphenicol, and kanamycin.

In any one of the embodiments described herein, the pharmaceutical composition further includes one or more pharmaceutically acceptable excipients.

In another aspect, a method of treating, preventing, or reducing the risk of a microbial infection in a patient is disclosed, including administering to the patient a pharmaceutical composition according to any one of the embodiments described herein.

In any one of the embodiments described herein, the microbial infection is a bacterial infection.

In any one of the embodiments described herein, the method includes treating, preventing, or reducing the risk of biofilms, hemotoxicity, and/or virulence.

In any one of the embodiments described herein, the administration is performed once daily.

In any one of the embodiments described herein, the microbial infection is clinically antibiotic resistant.

In any one of the embodiments described herein, the activity of the antimicrobial agent is potentiated by the compound.

In any one of the embodiments described herein, the antimicrobial agent is a macrolide, a folic acid synthesis inhibitor, a fluoroquinolone, an aminoglycoside, a monobactam, a cephalosporin, a glycopeptide, a β-lactam, a carbapenem, or a tetracycline.

In any one of the embodiments described herein, the antimicrobial agent is selected from the group consisting of erythromycin, trimethoprim, ciprofloxacin, streptomycin, aztreonam, cefalexin, vancomycin, ampicillin, doxycycline, and kanamycin.

In any one of the embodiments described herein, the antimicrobial agent is vancomycin or ampicillin.

In any one of the embodiments described herein, the microbe is Gram-positive bacteria, Gram-negative bacteria, or a mixture thereof.

In any one of the embodiments described herein, the microbe is selected from the group consisting of Bacillus cereus, Streptococcus pyogenes, Streptococcus pneumoniae, Staphylococcus aureus, Enterococcus faecium, Corynebacterium diphtheriae, Escherichia coli, Salmonella typhimurium, Pseudomonas aeruginosa, Klebsiella pneumoniae, Candida albicans, and mixtures thereof.

In any one of the embodiments described herein, the microbe is Staphylococcus aureus, Enterococcus faecium, or a mixture thereof.

In any one of the embodiments described herein, the microbe is methicillin-resistant Staphylococcus aureus (MRSA).

In any one of the embodiments described herein, the patient is a domestic animal.

In any one of the embodiments described herein, the patient is a mammal.

In any one of the embodiments described herein, the patient is a human.

In yet another aspect, a method of inhibiting or extinguishing the growth of one or more microbial cultures in vitro is disclosed, including administering to the microbial culture a pharmaceutical composition according to any one of the embodiments described herein.

In any one of the embodiments described herein, the microbial culture includes a bacterial culture.

In any one of the embodiments described herein, the microbial culture includes biofilms.

In any one of the embodiments described herein, the microbial culture includes microbes that are clinically antibiotic resistant.

In any one of the embodiments described herein, the microbial culture includes Staphylococcus aureus.

In yet another aspect, a method of treating, preventing, or reducing the risk of a bacterial infection in a patient is disclosed, including administering to a patient a compound of Formula A or B,

where

each occurrence of R₉ is independently selected from the group consisting of NH₂, NO₂, OH, CHO, halogen, and (C₁ to C₆)alkyl optionally substituted with one or more of halogen, OH, NH₂, NO₂, or CHO; and where R₉ is substituted on the phenyl ring of Formula A or the imidazole ring of Formula B;

m is 0 to 5;

each occurrence of R₁₀ is independently H, halogen, OH, CN, NO₂, OCF₃, (C₁ to C₆)alkyl, (C₂ to C₆)alkenyl, (C₂ to C₆)alkynyl, (C₁ to C₆)alkoxy, (C₃ to C₇)cycloalkyl, 3-7-membered heterocycle, (C₁ to C₆)alkylthio, NR_(a)R_(b), (C₁ to C₆)haloalkyl, (CH₂)_(p)(C₃ to C₇)cycloalkyl, (CH₂)_(p)OR_(a), (CH₂)_(p)SR_(a), (CH₂)_(p)NR_(a)R_(b), (CH₂)_(p)(C₁ to C₆)haloalkyl, or CH(indole)₂, in which said heterocycle includes at least one heteroatom selected from the group consisting of nitrogen, oxygen and sulfur and may be optionally substituted by from one to three groups which may be the same or different selected from the group consisting of halogen, OH, CN, (C₁ to C₄)alkyl, (C₁ to C₄)haloalkyl and (C₁ to C₄)alkoxy, or alternatively two R₁₀ taken together with the ring atoms they are connected to form a 3-7-membered aromatic ring; where R₁₀ is a group substituted on the indole ring and/or the phenyl ring of Formula A or on the indole ring and/or the imidazole ring of Formula B;

each of n, o, p and q is independently an integer from 0 to 4;

R₇ and R₈ are each independently H, halogen, OH, CN, OCF₃, (C₁ to C₆)alkyl, (C₂ to C₆)alkenyl, (C₂ to C₆)alkynyl, (C₁ to C₆)alkoxy, (C₃ to C₇)cycloalkyl, 3-7-membered heterocycle, (C₁ to C₆)alkylthio, NR_(a)R_(b), (C₁ to C₆)haloalkyl, (CH₂)_(p)(C₃ to C₇)cycloalkyl, (CH₂)_(p)OR_(a), (CH₂)_(p)SR_(a), (CH₂)_(p)NR_(a)R_(b), or (CH₂)_(p)(C₁ to C₆)haloalkyl, in which said heterocycle contains at least one heteroatom selected from the group consisting of nitrogen, oxygen, and sulfur and may be optionally substituted by from one to three groups which may be the same or different selected from the group consisting of halogen, OH, CN, (C₁ to C₄)alkyl, (C₁ to C₄)haloalkyl, and (C₁ to C₄)alkoxy;

each occurrence of R₁₁ is independently H, halogen, OH, CN, NO₂, OCF₃, (C₁ to C₆) alkyl, (C₂ to C₆)alkenyl, (C₂ to C₆)alkynyl, (C₁ to C₆)alkoxy, (C₃ to C₇)cycloalkyl, 3-7-membered heterocycle, (C₁ to C₆)alkylthio, NR_(a)R_(b), (C₁ to C₆)haloalkyl, (CH₂)_(p)(C₃ to C₇)cycloalkyl, (CH₂)_(p)OR_(a), (CH₂)_(p)SR_(a), or (CH₂)_(p)NR_(a)R_(b), in which said heterocycle includes at least one heteroatom selected from the group consisting of nitrogen, oxygen and sulfur and may be optionally substituted by from one to three groups which may be the same or different selected from the group consisting of halogen, OH, CN, (C₁ to C₄)alkyl, (C₁ to C₄)haloalkyl and (C₁ to C₄)alkoxy;

R_(a) and R_(b) are each independently H, (C₁ to C₆)alkyl, (C₂ to C₆)alkenyl, or (C₃ to C₇)cycloalkyl; and

x is absent; or alternatively x is a positive charge and Rn is absent.

In any one of the embodiments described herein, the method includes one or more pharmaceutically acceptable excipients.

Any one of the embodiments disclosed herein may be properly combined with any other embodiment disclosed herein. The combination of any one of the embodiments disclosed herein with any other embodiments disclosed herein is expressly contemplated. Specifically, the selection of one or more embodiments for one substituent group can be properly combined with the selection of one or more particular embodiments for any other substituent group. Such combination can be made in any one or more embodiments of the application described herein or any formula described herein.

DESCRIPTION OF THE DRAWINGS

The invention is described with reference to the following figures, which are presented for the purpose of illustration only and are not intended to be limiting. In the drawings:

FIG. 1 depicts the ¹H NMR spectrum of SP-BIM 1 taken in CDCl₃, according to one or more embodiments.

FIG. 2 depicts the ¹³C NMR spectrum of SP-BIM 1 taken in CDCl₃, according to one or more embodiments.

FIG. 3A depicts the ¹H NMR spectrum of SP-BIM 8 taken in DMSO-d6, according to one or more embodiments.

FIG. 3B depicts the ¹³C NMR spectrum of SP-BIM 8 taken in DMSO-d6, according to one or more embodiments.

FIG. 4A depicts the ¹H NMR spectrum of SP-BIM 9 taken in DMSO-d6, according to one or more embodiments.

FIG. 4B depicts the ¹³C NMR spectrum of SP-BIM 9 taken in DMSO-d6, according to one or more embodiments.

FIG. 5A depicts the ¹H NMR spectrum of SP-BIM 13 taken in DMSO-d6, according to one or more embodiments.

FIG. 5B depicts the ¹³C NMR spectrum of SP-BIM 13 taken in DMSO-d6, according to one or more embodiments.

FIG. 6A depicts the ¹H NMR spectrum of SP-BIM 21 taken in CD₃OD, according to one or more embodiments.

FIG. 6B depicts the ¹³C NMR spectrum of SP-BIM 21 taken in CD₃OD, according to one or more embodiments.

FIG. 7A depicts the ¹H NMR spectrum of SP-BIM 27 taken in CD₃OD, according to one or more embodiments.

FIG. 7B depicts the ¹³C NMR spectrum of SP-BIM 27 taken in CD₃OD, according to one or more embodiments.

FIG. 8A depicts the ¹H NMR spectrum of SP-BIM 28 taken in CD₃OD, according to one or more embodiments.

FIG. 8B depicts the ¹³C NMR spectrum of SP-BIM 28 taken in CD₃OD, according to one or more embodiments.

FIG. 9A depicts the ¹H NMR spectrum of SP-BIM 29 taken in CD₃OD, according to one or more embodiments.

FIG. 9B depicts the ¹³C NMR spectrum of SP-BIM 29 taken in CD₃OD, according to one or more embodiments.

FIG. 10A depicts the in vivo adjuvant efficacy, measured as methicillin-resistant Staphylococcus aureus (“MRSA”) load in liver, of SP-BIM 13 when administered to mice infected with a non-lethal dose of MRSA HS 10132 strain, according to one or more embodiments.

FIG. 10B depicts the in vivo adjuvant efficacy, measured as MRSA load in spleen, of SP-BIM 13 when administered to mice infected with a non-lethal dose of MRSA HS 10132 strain, according to one or more embodiments.

FIGS. 11A-11B depict the in vivo adjuvant efficacy of SP-BIM 13 when administered to mice infected with a lethal dose of MRSA HS 10132 strain, according to one or more embodiments.

FIG. 12 depicts the in vivo adjuvant efficacy of SP-BIM 9 when administered to mice infected with a non-lethal dose of MRSA HS 10132 strain, according to one or more embodiments.

FIG. 13 depicts the efficacy of SP-BIMs 2, 3, 5, 6, 9, 11, 13, 15, and 18 in inhibiting biofilm formation of Staphylococcus aureus at different concentrations, according to one or more embodiments.

FIG. 14 depicts the efficacy of SP-BIM 13 in preventing hemolysin production in Staphylococcus aureus, according to one or more embodiments.

FIGS. 15A-15C depict in silico predictions of the six best docking poses of SP-BIMs 2, 9, 12, 13, and 17 onto the catalytic domain of Bacillus cereus histidine kinase (HK) walK (PDB: 3SL2, chain A, residues 451-611), according to one or more embodiments.

FIG. 16A depicts the efficacy of SP-BIM 13 in regulating expression of the global regulator genes Staphylococcal accessory regulator (sarA), accessory gene regulator (agr), and RNA III, according to one or more embodiments.

FIG. 16B depicts the efficacy of SP-BIM 13 on expression of downstream Staphylococcal genes including mecA, blaZ and fnbA, according to one or more embodiments.

FIG. 17 depicts the hemotoxicity of SP-BIMs 5-7, 11, 13, 15, and 18, according to one or more embodiments.

FIG. 18A depicts relative mice weights after treatment with SP-BIM 13, respectively, according to one or more embodiments.

FIG. 18B depicts the mass of food consumed by mice after treatment with SP-BIM 13, respectively, according to one or more embodiments.

FIG. 19A shows in silico docking pose of SP-BIM 33 onto the catalytic domain of Bacillus cereus histidine kinase (HK) walK (PDB: 3SL2, chain A, residues 451-611), according to one or more embodiments.

FIG. 19B shows in silico docking pose of SP-BIM 34 onto the catalytic domain of Bacillus cereus histidine kinase (HK) walK (PDB: 3SL2, chain A, residues 451-611), according to one or more embodiments.

DETAILED DESCRIPTION Definitions

The following are definitions of terms used in the present specification. The initial definition provided for a group or term herein applies to that group or term throughout the present specification individually or as part of another group, unless otherwise indicated.

The terms “alkyl” and “alk” refer to a straight or branched chain alkane (hydrocarbon) radical containing from 1 to 12 carbon atoms, preferably from 1 to 6 carbon atoms. Exemplary “alkyl” groups include methyl, ethyl, propyl, isopropyl, n-butyl, t-butyl, isobutyl pentyl, hexyl, isohexyl, heptyl, 4,4-dimethylpentyl, octyl, 2,2,4-trimethylpentyl, nonyl, decyl, undecyl, dodecyl, and the like. The term “(C₁-C₄)alkyl” refers to a straight or branched chain alkane (hydrocarbon) radical containing from 1 to 4 carbon atoms, such as methyl, ethyl, propyl, isopropyl, n-butyl, t-butyl, and isobutyl. The term “(C₁-C₆)alkyl” refers to a straight or branched chain alkane (hydrocarbon) radical containing from 1 to 6 carbon atoms, such as n-hexyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 2,3-dimethylbutyl, 2,2-dimethylbutyl, in addition to those exemplified for “(C₁-C₄)alkyl.” “Substituted alkyl” refers to an alkyl group substituted with one or more substituents, preferably from 1 to 4 substituents, at any available point of attachment. Exemplary substituents include but are not limited to one or more of the following groups: H, halogen (e.g., a single halogen substituent or multiple halo substituents forming, in the latter case, groups such as CF₃ or an alkyl group bearing Cl₃), cyano, nitro, oxo (i.e., ═O), CF₃, OCF₃, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, heterocycle, aryl, OR_(a), SR_(a), S(═O)R_(e), S(═O)₂R_(e), P(═O)₂R_(e), S(═O)₂OR_(e), P(═O)₂OR_(e), NR_(b)R_(c), NR_(b)S(═O)₂R_(e), NR_(b)P(═O)₂R_(e), S(═O)₂NR_(b)R_(c), P(═O)₂NR_(b)R_(c), C(═O)OR_(d), C(═O)R_(a), C(═O)NR_(b)R_(c), OC(═O)R_(a), OC(═O)NR_(b)R_(c), NR_(b)C(═O)OR_(e), NR_(d)C(═O)NR_(b)R_(c), NR_(d)S(═O)₂NR_(b)R_(c), NR_(d)P(═O)₂NR_(b)R_(c), NR_(b)C(═O)R_(a), or NR_(b)P(═O)₂R_(e), where each occurrence of R_(a) is independently H, alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, heterocycle, or aryl; each occurrence of R_(b), R_(c), and R_(d) is independently hydrogen, alkyl, cycloalkyl, heterocycle, aryl, or said R_(b) and R_(c) together with the N to which they are bonded optionally form a heterocycle; and each occurrence of R_(e) is independently alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, heterocycle, or aryl. In the aforementioned exemplary substituents, groups such as alkyl, cycloalkyl, alkenyl, alkynyl, cycloalkenyl, heterocycle, and aryl can themselves be optionally substituted.

The term “alkenyl” refers to a straight or branched chain hydrocarbon radical containing from 2 to 12 carbon atoms and at least one carbon-carbon double bond. Examples of such groups include, but are not limited to, ethenyl or allyl. The term “C₂-C₆ alkenyl” refers to a straight or branched chain hydrocarbon radical containing from 2 to 6 carbon atoms and at least one carbon-carbon double bond, such as ethylenyl, propenyl, 2-propenyl, (E)-but-2-enyl, (Z)-but-2-enyl, 2-methy(E)-but-2-enyl, 2-methy(Z)-but-2-enyl, 2,3-dimethy-but-2-enyl, (Z)-pent-2-enyl, (E)-pent-1-enyl, (Z)-hex-1-enyl, (E)-pent-2-enyl, (Z)-hex-2-enyl, (E)-hex-2-enyl, (Z)-hex-1-enyl, (E)-hex-1-enyl, (Z)-hex-3-enyl, (E)-hex-3-enyl, and (E)-hex-1,3-dienyl. “Substituted alkenyl” refers to an alkenyl group substituted with one or more substituents, preferably from 1 to 4 substituents, at any available point of attachment. Exemplary substituents include but are not limited to one or more of the following groups: H, halogen (e.g., a single halogen substituent or multiple halo substituents forming, in the latter case, groups such as CF₃ or an alkyl group bearing Cl₃), cyano, nitro, oxo (i.e., ═O), CF₃, OCF₃, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, heterocycle, aryl, OR_(a), SR_(a), S(═O)R_(e), S(═O)₂R_(e), P(═O)₂R_(e), S(═O)₂OR_(e), P(═O)₂OR_(e), NR_(b)R_(c), NR_(b)S(═O)₂R_(e), NR_(b)P(═O)₂R_(e), S(═O)₂NR_(b)R_(c), P(═O)₂NR_(b)R_(c), C(═O)OR_(d), C(═O)R_(a), C(═O)NR_(b)R_(c), OC(═O)R_(a), OC(═O)NR_(b)R_(c), NR_(b)C(═O)OR_(e), NR_(d)C(═O)NR_(b)R_(c), NR_(d)S(═O)₂NR_(b)R_(c), NR_(d)P(═O)₂NR_(b)R_(c), NR_(b)C(═O)R_(a), or NR_(b)P(═O)₂R_(e), where each occurrence of R_(a) is independently H, alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, heterocycle, or aryl; each occurrence of R_(b), R_(c), and R_(d) is independently hydrogen, alkyl, cycloalkyl, heterocycle, aryl, or said R_(b) and R_(c) together with the N to which they are bonded optionally form a heterocycle; and each occurrence of R_(e) is independently alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, heterocycle, or aryl. The exemplary substituents can themselves be optionally substituted.

The term “alkynyl” refers to a straight or branched chain hydrocarbon radical containing from 2 to 12 carbon atoms and at least one carbon-carbon triple bond. An example of such groups includes, but is not limited to, ethynyl. The term “C₂-C₆ alkynyl” refers to a straight or branched chain hydrocarbon radical containing from 2 to 6 carbon atoms and at least one carbon-carbon triple bond, such as ethynyl, prop-1-ynyl, prop-2-ynyl, but-1-ynyl, but-2-ynyl, pent-1-ynyl, pent-2-ynyl, hex-1-ynyl, hex-2-ynyl, and hex-3-ynyl. “Substituted alkynyl” refers to an alkynyl group substituted with one or more substituents, preferably from 1 to 4 substituents, at any available point of attachment. Exemplary substituents include but are not limited to one or more of the following groups: H, halogen (e.g., a single halogen substituent or multiple halo substituents forming, in the latter case, groups such as CF₃ or an alkyl group bearing Cl₃), cyano, nitro, oxo (i.e., ═O), CF₃, OCF₃, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, heterocycle, aryl, OR_(a), SR_(a), S(═O)R_(e), S(═O)₂R_(e), P(═O)₂R_(e), S(═O)₂OR_(e), P(═O)₂OR_(e), NR_(b)R_(c), NR_(b)S(═O)₂R_(e), NR_(b)P(═O)₂R_(e), S(═O)₂NR_(b)R_(c), P(═O)₂NR_(b)R_(c), C(═O)OR_(d), C(═O)R_(a), C(═O)NR_(b)R_(c), OC(═O)R_(a), OC(═O)NR_(b)R_(c), NR_(b)C(═O)OR_(e), NR_(d)C(═O)NR_(b)R_(c), NR_(d)S(═O)₂NR_(b)R_(c), NR_(d)P(═O)₂NR_(b)R_(c), NR_(b)C(═O)R_(a), or NR_(b)P(═O)₂R_(e), where each occurrence of R_(a) is independently H, alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, heterocycle, or aryl; each occurrence of R_(b), R_(c), and R_(d) is independently H, alkyl, cycloalkyl, heterocycle, aryl, or said R_(b) and R_(c) together with the N to which they are bonded optionally form a heterocycle; and each occurrence of R_(e) is independently alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, heterocycle, or aryl. The exemplary substituents can themselves be optionally substituted.

The term “cycloalkyl” refers to a fully saturated cyclic hydrocarbon group containing from 1 to 4 rings and from 3 to 8 carbons per ring. “C₃-C₇ cycloalkyl” refers to cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, or cycloheptyl. “Substituted cycloalkyl” refers to a cycloalkyl group substituted with one or more substituents, preferably from 1 to 4 substituents, at any available point of attachment. Exemplary substituents include but are not limited to one or more of the following groups: H, halogen (e.g., a single halogen substituent or multiple halo substituents forming, in the latter case, groups such as CF₃ or an alkyl group bearing Cl₃), cyano, nitro, oxo (i.e., ═O), CF₃, OCF₃, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, heterocycle, aryl, OR_(a), SR_(a), S(═O)R_(e), S(═O)₂R_(e), P(═O)₂R_(e), S(═O)₂OR_(e), P(═O)₂OR_(e), NR_(b)R_(c), NR_(b)S(═O)₂R_(e), NR_(b)P(═O)₂R_(e), S(═O)₂NR_(b)R_(c), P(═O)₂NR_(b)R_(c), C(═O)OR_(d), C(═O)R_(a), C(═O)NR_(b)R_(c), OC(═O)R_(a), OC(═O)NR_(b)R_(c), NR_(b)C(═O)OR_(e), NR_(d)C(═O)NR_(b)R_(c), NR_(d)S(═O)₂NR_(b)R_(c), NR_(d)P(═O)₂NR_(b)R_(c), NR_(b)C(═O)R_(a), or NR_(b)P(═O)₂R_(e), where each occurrence of R_(a) is independently H, alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, heterocycle, or aryl; each occurrence of R_(b), R_(c), and R_(d) is independently H, alkyl, cycloalkyl, heterocycle, aryl, or said R_(b) and R_(c) together with the N to which they are bonded optionally form a heterocycle; and each occurrence of R_(e) is independently alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, heterocycle, or aryl. The exemplary substituents can themselves be optionally substituted. Exemplary substituents also include, but are not limited to, spiro-attached or fused cyclic substituents, especially spiro-attached cycloalkyl, spiro-attached cycloalkenyl, spiro-attached heterocycle (excluding heteroaryl), fused cycloalkyl, fused cycloalkenyl, fused heterocycle, or fused aryl, where the aforementioned cycloalkyl, cycloalkenyl, heterocycle, and aryl substituents can themselves be optionally substituted.

The term “cycloalkenyl” refers to a partially unsaturated cyclic hydrocarbon group containing from 1 to 4 rings and from 3 to 8 carbons per ring. Examples of such groups include, but are not limited to, cyclobutenyl, cyclopentenyl, cyclohexenyl, etc. “Substituted cycloalkenyl” refers to a cycloalkenyl group substituted with one more substituents, preferably from 1 to 4 substituents, at any available point of attachment. Exemplary substituents include but are not limited to one or more of the following groups: H, halogen (e.g., a single halogen substituent or multiple halo substituents forming, in the latter case, groups such as CF₃ or an alkyl group bearing Cl₃), cyano, nitro, oxo (i.e., ═O), CF₃, OCF₃, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, heterocycle, aryl, OR_(a), SR_(a), S(═O)R_(e), S(═O)₂R_(e), P(═O)₂R_(e), S(═O)₂OR_(e), P(═O)₂OR_(e), NR_(b)R_(c), NR_(b)S(═O)₂R_(e), NR_(b)P(═O)₂R_(e), S(═O)₂NR_(b)R_(c), P(═O)₂NR_(b)R_(c), C(═O)OR_(d), C(═O)R_(a), C(═O)NR_(b)R_(c), OC(═O)R_(a), OC(═O)NR_(b)R_(c), NR_(b)C(═O)OR_(e), NR_(d)C(═O)NR_(b)R_(c), NR_(d)S(═O)₂NR_(b)R_(c), NR_(d)P(═O)₂NR_(b)R_(c), NR_(b)C(═O)R_(a), or NR_(b)P(═O)₂R_(e), where each occurrence of R_(a) is independently H, alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, heterocycle, or aryl; each occurrence of R_(b), R_(c), and R_(d) is independently H, alkyl, cycloalkyl, heterocycle, aryl, or said R_(b) and R_(c) together with the N to which they are bonded optionally form a heterocycle; and each occurrence of R_(e) is independently alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, heterocycle, or aryl. The exemplary substituents can themselves be optionally substituted. Exemplary substituents also include, but are not limited to, spiro-attached or fused cyclic substituents, especially spiro-attached cycloalkyl, spiro-attached cycloalkenyl, spiro-attached heterocycle (excluding heteroaryl), fused cycloalkyl, fused cycloalkenyl, fused heterocycle, or fused aryl, where the aforementioned cycloalkyl, cycloalkenyl, heterocycle, and aryl substituents can themselves be optionally substituted.

The term “aryl” refers to cyclic, aromatic hydrocarbon groups that have from 1 to 5 aromatic rings, especially monocyclic or bicyclic groups such as phenyl, biphenyl, or naphthyl. Where containing two or more aromatic rings (bicyclic, etc.), the aromatic rings of the aryl group may be joined at a single point (e.g., biphenyl), or fused (e.g., naphthyl, phenanthrenyl and the like). “Substituted aryl” refers to an aryl group substituted by one or more substituents, preferably from 1 to 3 substituents, at any available point of attachment. Exemplary substituents include but are not limited to one or more of the following groups: H, halogen (e.g., a single halogen substituent or multiple halo substituents forming, in the latter case, groups such as CF₃ or an alkyl group bearing Cl₃), cyano, nitro, oxo (i.e., ═O), CF₃, OCF₃, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, heterocycle, aryl, OR_(a), SR_(a), S(═O)R_(e), S(═O)₂R_(e), P(═O)₂R_(e), S(═O)₂OR_(e), P(═O)₂OR_(e), NR_(b)R_(c), NR_(b)S(═O)₂R_(e), NR_(b)P(═O)₂R_(e), S(═O)₂NR_(b)R_(c), P(═O)₂NR_(b)R_(c), C(═O)OR_(d), C(═O)R_(a), C(═O)NR_(b)R_(c), OC(═O)R_(a), OC(═O)NR_(b)R_(c), NR_(b)C(═O)OR_(e), NR_(d)C(═O)NR_(b)R_(c), NR_(d)S(═O)₂NR_(b)R_(c), NR_(d)P(═O)₂NR_(b)R_(c), NR_(b)C(═O)R_(a), or NR_(b)P(═O)₂R_(e), where each occurrence of R_(a) is independently H, alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, heterocycle, or aryl; each occurrence of R_(b), R_(c), and R_(d) is independently H, alkyl, cycloalkyl, heterocycle, aryl, or said R_(b) and R_(c) together with the N to which they are bonded optionally form a heterocycle; and each occurrence of R_(e) is independently alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, heterocycle, or aryl. The exemplary substituents can themselves be optionally substituted. Exemplary substituents also include, but are not limited to, fused cyclic groups, especially fused cycloalkyl, fused cycloalkenyl, fused heterocycle, or fused aryl, where the aforementioned cycloalkyl, cycloalkenyl, heterocycle, and aryl substituents can themselves be optionally substituted.

The terms “heterocycle” and “heterocyclic” refer to fully saturated, or partially or fully unsaturated, including aromatic (i.e., “heteroaryl”) cyclic groups (e.g., 4 to 7 membered monocyclic, 7 to 11 membered bicyclic, or 8 to 16 membered tricyclic ring systems) which have at least one heteroatom in at least one carbon atom-containing ring. Each ring of the heterocyclic group containing a heteroatom may have 1, 2, 3, or 4 heteroatoms selected from nitrogen atoms, oxygen atoms, and/or sulfur atoms, where the nitrogen and sulfur heteroatoms may optionally be oxidized and the nitrogen heteroatoms may optionally be quaternized. The term “heteroarylium” refers to a heteroaryl group bearing a quaternary nitrogen atom and, thus, a positive charge. The heterocyclic group may be attached to the remainder of the molecule at any heteroatom or carbon atom of the ring or ring system. Exemplary monocyclic heterocyclic groups include, but are not limited to, azetidinyl, pyrrolidinyl, pyrrolyl, pyrazolyl, oxetanyl, pyrazolinyl, imidazolyl, imidazolinyl, imidazolidinyl, oxazolyl, oxazolidinyl, isoxazolinyl, isoxazolyl, thiazolyl, thiadiazolyl, thiazolidinyl, isothiazolyl, isothiazolidinyl, furyl, tetrahydrofuryl, thienyl, oxadiazolyl, piperidinyl, piperazinyl, 2-oxopiperazinyl, 2-oxopiperidinyl, 2-oxopyrrolodinyl, 2-oxoazepinyl, azepinyl, hexahydrodiazepinyl, 4-piperidonyl, pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, triazinyl, triazolyl, tetrazolyl, tetrahydropyranyl, morpholinyl, thiamorpholinyl, thiamorpholinyl sulfoxide, thiamorpholinyl sulfone, 1,3-dioxolane and tetrahydro-1,1-dioxothienyl, and the like. Exemplary bicyclic heterocyclic groups include indolyl, isoindolyl, benzothiazolyl, benzoxazolyl, benzoxadiazolyl, benzothienyl, benzo[d][1,3]dioxolyl, 2,3-dihydrobenzo[b][1,4]dioxinyl, quinuclidinyl, quinolinyl, tetrahydroisoquinolinyl, isoquinolinyl, benzimidazolyl, benzopyranyl, indolizinyl, benzofuryl, benzofurazanyl, chromonyl, coumarinyl, benzopyranyl, cinnolinyl, quinoxalinyl, indazolyl, pyrrolopyridyl, furopyridinyl (such as furo[2,3-c]pyridinyl, furo[3,2-b]pyridinyl] or furo[2,3-b]pyridinyl), dihydroisoindolyl, dihydroquinazolinyl (such as 3,4-dihydro-4-oxo-quinazolinyl), triazinylazepinyl, tetrahydroquinolinyl, and the like. Exemplary tricyclic heterocyclic groups include, but are not limited to, carbazolyl, benzidolyl, phenanthrolinyl, acridinyl, phenanthridinyl, xanthenyl, and the like.

“Substituted heterocycle” and “substituted heterocyclic” (such as “substituted heteroaryl”) refer to heterocycle or heterocyclic groups substituted with one or more substituents, preferably from 1 to 4 substituents, at any available point of attachment. Exemplary substituents include but are not limited to one or more of the following groups: H, halogen (e.g., a single halogen substituent or multiple halo substituents forming, in the latter case, groups such as CF₃ or an alkyl group bearing Cl₃), cyano, nitro, oxo (i.e., ═O), CF₃, OCF₃, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, heterocycle, aryl, OR_(a), SR_(a), S(═O)R_(e), S(═O)₂R_(e), P(═O)₂R_(e), S(═O)₂OR_(e), P(═O)₂OR_(e), NR_(b)R_(c), NR_(b)S(═O)₂R_(e), NR_(b)P(═O)₂R_(e), S(═O)₂NR_(b)R_(c), P(═O)₂NR_(b)R_(c), C(═O)OR_(d), C(═O)R_(a), C(═O)NR_(b)R_(c), OC(═O)R_(a), OC(═O)NR_(b)R_(c), NR_(b)C(═O)OR_(e), NR_(d)C(═O)NR_(b)R_(c), NR_(d)S(═O)₂NR_(b)R_(c), NR_(d)P(═O)₂NR_(b)R_(c), NR_(b)C(═O)R_(a), or NR_(b)P(═O)₂R_(e), where each occurrence of R_(a) is independently H, alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, heterocycle, or aryl; each occurrence of R_(b), R_(c), and R_(d) is independently H, alkyl, cycloalkyl, heterocycle, aryl, or said R_(b) and R_(c) together with the N to which they are bonded optionally form a heterocycle; and each occurrence of R_(e) is independently alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, heterocycle, or aryl. The exemplary substituents can themselves be optionally substituted. Exemplary substituents also include, but are not limited to, spiro-attached or fused cyclic substituents at any available point or points of attachment, especially spiro-attached cycloalkyl, spiro-attached cycloalkenyl, spiro-attached heterocycle (excluding heteroaryl), fused cycloalkyl, fused cycloalkenyl, fused heterocycle, or fused aryl, where the aforementioned cycloalkyl, cycloalkenyl, heterocycle, and aryl substituents can themselves be optionally substituted.

The term “alkylamino” refers to a group having the structure —NHR′, where R′ is H, alkyl or substituted alkyl, or cycloalkyl or substituted cycloalkyl, as defined herein. Examples of alkylamino groups include, but are not limited to, methylamino, ethylamino, n-propylamino, iso-propylamino, cyclopropylamino, n-butylamino, tert-butylamino, neopentylamino, n-pentylamino, hexylamino, cyclohexylamino, and the like.

The term “dialkylamino” refers to a group having the structure —NRR′, where R and R′ are each independently alkyl or substituted alkyl, cycloalkyl or substituted cycloalkyl, cycloalkenyl or substituted cyclolalkenyl, aryl or substituted aryl, or heterocyclyl or substituted heterocyclyl, as defined herein. R and R′ may be the same or different in an dialkylamino moiety. Examples of dialkylamino groups include, but are not limited to, dimethylamino, methyl ethylamino, diethylamino, methylpropylamino, di(n-propyl)amino, di(iso-propyl)amino, di(cyclopropyl)amino, di(n-butyl)amino, di(tert-butyl)amino, di(neopentyl)amino, di(n-pentyl)amino, di(hexyl)amino, di(cyclohexyl)amino, and the like. In certain embodiments, R and R′ are linked to form a cyclic structure. The resulting cyclic structure may be aromatic or non-aromatic. Examples of cyclic diaminoalkyl groups include, but are not limited to, aziridinyl, pyrrolidinyl, piperidinyl, morpholinyl, pyrrolyl, imidazolyl, 1,3,4-trianolyl, and tetrazolyl.

The terms “halogen” or “halo” refer to chlorine, bromine, fluorine or iodine.

Unless otherwise indicated, any heteroatom with unsatisfied valences is assumed to have hydrogen atoms sufficient to satisfy the valences.

The compounds disclosed herein may form salts which are also within the scope of this disclosure. Reference to a compound disclosed herein is understood to include reference to salts thereof, unless otherwise indicated. The term “salt(s)”, as employed herein, denotes acidic and/or basic salts formed with inorganic and/or organic acids and bases. In addition, when a compound disclosed herein contains both a basic moiety, such as, but not limited to, a pyridine or imidazole, and an acidic moiety such as, but not limited to, a carboxylic acid, zwitterions (“inner salts”) may be formed and are included within the term “salt(s)” as used herein. Pharmaceutically acceptable (i.e., non-toxic, physiologically acceptable) salts are preferred, although other salts are also useful, e.g., in isolation or purification steps which may be employed during preparation. Salts of a compound disclosed herein may be formed, for example, by reacting a compound of formula A, A′, or B with an amount of acid or base, such as an equivalent amount, in a medium such as one in which the salt precipitates or in an aqueous medium followed by lyophilization.

The compounds disclosed herein which contain a basic moiety, such as, but not limited to, an amine or a pyridine or imidazole ring, may form salts with a variety of organic and inorganic acids. Exemplary acid addition salts include, but are not limited to, acetates (such as those formed with acetic acid or trihaloacetic acid, e.g., trifluoroacetic acid), adipates, alginates, ascorbates, aspartates, benzoates, benzenesulfonates, bisulfates, borates, butyrates, citrates, camphorates, camphorsulfonates, cyclopentanepropionates, digluconates, dodecylsulfates, ethanesulfonates, fumarates, glucoheptanoates, glycerophosphates, hemisulfates, heptanoates, hexanoates, hydrochlorides, hydrobromides, hydroiodides, hydroxyethanesulfonates (e.g., 2-hydroxyethanesulfonates), lactates, maleates, methanesulfonates, naphthalenesulfonates (e.g., 2-naphthalenesulfonates), nicotinates, nitrates, oxalates, pectinates, persulfates, phenylpropionates (e.g., 3-phenylpropionates), phosphates, picrates, pivalates, propionates, salicylates, succinates, sulfates (such as those formed with sulfuric acid), sulfonates, tartrates, thiocyanates, toluenesulfonates, such as tosylates, undecanoates, and the like.

Compounds disclosed herein which contain an acidic moiety, such as, but not limited to, a carboxylic acid, may form salts with a variety of organic and inorganic bases. Exemplary basic salts include, but are not limited to, ammonium salts, alkali metal salts, such as sodium, lithium and potassium salts, alkaline earth metal salts, such as calcium and magnesium salts, salts with organic bases (e.g., organic amines), such as benzathines, dicyclohexylamines, hydrabamines (formed with N,N-bis(dehydroabietyl) ethylenediamine), N-methyl-D-glucamines, N-methyl-D-glycamides, and t-butyl amines, and salts with amino acids such as arginine, lysine, and the like. Basic nitrogen-containing groups may be quaternized with agents such as lower alkyl halides (e.g., methyl, ethyl, propyl, and butyl chlorides, bromides, and iodides), dialkyl sulfates (e.g., dimethyl, diethyl, dibutyl, and diamyl sulfates), long chain halides (e.g., decyl, lauryl, myristyl, and stearyl chlorides, bromides, and iodides), aralkyl halides (e.g., benzyl and phenethyl bromides), and others.

Prodrugs and solvates of the compounds disclosed herein are also contemplated herein. The term “prodrug” as employed herein denotes a compound that, upon administration to a subject, undergoes chemical conversion by metabolic or chemical processes to yield a compound as disclosed herein, or a salt and/or solvate thereof. Solvates of the compounds disclosed herein include, for example, hydrates.

Compounds disclosed herein, and salts or solvates thereof, may exist in their tautomeric form (for example, as an amide or imino ether). All such tautomeric forms are contemplated herein as part of the present disclosure.

All stereoisomers of the present compounds (for example, those which may exist due to asymmetric carbons on various substituents), including enantiomeric forms and diastereomeric forms, are contemplated within the scope of this disclosure. Individual stereoisomers of the compounds disclosed herein may, for example, be substantially free of other isomers (e.g., as a pure or substantially pure optical isomer having a specified activity), or may be admixed, for example, as racemates or with all other, or other selected, stereoisomers. The chiral centers of the compounds disclosed herein may have the S or R configuration as defined by the International Union of Pure and Applied Chemistry (IUPAC) 1974 Recommendations. The racemic forms can be resolved by physical methods, such as, for example, fractional crystallization, separation or crystallization of diastereomeric derivatives, or separation by chiral column chromatography. The individual optical isomers can be obtained from the racemates by any suitable method, including, without limitation, conventional methods, such as, for example, salt formation with an optically active acid followed by crystallization.

Compounds disclosed herein are, subsequent to their preparation, preferably isolated and purified to obtain a composition containing an amount by weight equal to or greater than 90%, for example, equal to greater than 95%, equal to or greater than 99% pure (“substantially pure” compound of formula A, A′, or B which is then used or formulated as described herein). Such “substantially pure” compounds as disclosed herein are also contemplated herein as part of the present disclosure.

All configurational isomers of the compounds disclosed herein are contemplated, either in admixture or in pure or substantially pure form. The definition of compounds disclosed herein embraces both cis (Z) and trans (E) alkene isomers, as well as cis and trans isomers of cyclic hydrocarbon or heterocyclic rings.

Throughout the specifications, groups, and substituents thereof may be chosen to provide stable moieties and compounds.

Definitions of specific functional groups and chemical terms are described in more detail below. For purposes of this disclosure, the chemical elements are identified in accordance with the Periodic Table of the Elements, CAS Version, Handbook of Chemistry and Physics, 75^(th) Ed., inside cover, and specific functional groups are generally defined as described therein. Additionally, general principles of organic chemistry, as well as specific functional moieties and reactivity, are described in Sorrell T, Organic Chemistry, University Science Books, Sausalito, Calif.: 1999, the entire contents of which are incorporated herein by reference.

Certain compounds of the present disclosure may exist in particular geometric or stereoisomeric forms. The present disclosure contemplates all such compounds, including cis- and trans-isomers, R- and S-enantiomers and diastereomers, (D)-isomers, (L)-isomers, the racemic mixtures thereof, and other mixtures thereof, as falling within the scope of the disclosure. Additional asymmetric carbon atoms may be present in a substituent such as an alkyl group. All such isomers, as well as mixtures thereof, are intended to be included in this disclosure.

Isomeric mixtures containing any of a variety of isomer ratios may be utilized in accordance with the present disclosure. For example, where only two isomers are combined, mixtures containing 50:50, 60:40, 70:30, 80:20, 90:10, 95:5, 96:4, 97:3, 98:2, 99:1, or 100:0 isomer ratios are all contemplated by the present disclosure. Those of ordinary skill in the art will readily appreciate that analogous ratios are contemplated for more complex isomer mixtures.

The compounds disclosed herein also include isotopically labeled compounds, which are identical to the compounds disclosed herein, but for the fact that one or more atoms are replaced by an atom having an atomic mass or mass number different from the atomic mass or mass number usually found in nature. Examples of isotopes that can be incorporated into compounds as disclosed herein include isotopes of hydrogen, carbon, nitrogen, oxygen, phosphorous, sulfur, fluorine, and chlorine, such as ²H, ³H, ¹³C, ¹¹C, ¹⁴C, ¹⁵N, ¹⁸O, ¹⁷O, ³¹P, ³²P, ³⁵S, ¹⁸F, and ³⁶Cl, respectively. Compounds disclosed herein, or an enantiomer, diastereomer, tautomer, or pharmaceutically acceptable salt or solvate thereof, which contain the aforementioned isotopes and/or other isotopes of other atoms are within the scope of this disclosure. Certain isotopically labeled compounds of the present disclosure, for example those into which radioactive isotopes such as ³H and ¹⁴C are incorporated, are useful in drug and/or substrate tissue distribution assays. Tritiated, i.e., ³H, and carbon-14, i.e., ¹⁴C, isotopes are particularly preferred for their ease of preparation and detectability. Further, substitution with heavier isotopes such as deuterium, i.e., ²H, can afford certain therapeutic advantages resulting from greater metabolic stability, for example increased in vivo half-life or reduced dosage requirements and, hence, may be preferred in some circumstances. Isotopically labeled compounds can generally be prepared by carrying out the procedures disclosed in the Schemes and/or in the Examples below, by substituting a readily available isotopically labeled reagent for a non-isotopically labeled reagent.

If, for instance, a particular enantiomer of a compound of the present disclosure is desired, it may be prepared by asymmetric synthesis, or by derivation with a chiral auxiliary, where the resulting diastereomeric mixture is separated and the auxiliary group cleaved to provide the pure desired enantiomers. Alternatively, where the molecule contains a basic functional group, such as amino, or an acidic functional group, such as carboxyl, diastereomeric salts are formed with an appropriate optically-active acid or base, followed by resolution of the diastereomers thus formed by fractional crystallization or chromatographic means well known in the art, and subsequent recovery of the pure enantiomers.

It will be appreciated that the compounds, as described herein, may be substituted with any number of substituents or functional moieties. In general, the term “substituted” whether preceded by the term “optionally” or not, and substituents contained in formulas of this disclosure, refer to the replacement of hydrogen radicals in a given structure with the radical of a specified substituent. When more than one position in any given structure may be substituted with more than one substituent selected from a specified group, the substituent may be either the same or different at every position. As used herein, the term “substituted” is contemplated to include all permissible substituents of organic compounds. In a broad aspect, the permissible substituents include acyclic and cyclic, branched and unbranched, carbocyclic and heterocyclic, and aromatic and nonaromatic substituents of organic compounds. For purposes of this disclosure, heteroatoms such as nitrogen may have hydrogen substituents and/or any permissible substituents of organic compounds described herein which satisfy the valences of the heteroatoms. Furthermore, this disclosure is not intended to be limited in any manner by the permissible substituents of organic compounds. Combinations of substituents and variables envisioned by this disclosure are preferably those that result in the formation of stable compounds useful in the treatment, for example, of infectious diseases or proliferative disorders. The term “stable”, as used herein, preferably refers to compounds which possess stability sufficient to allow manufacture and which maintain the integrity of the compound for a sufficient period of time to be detected and preferably for a sufficient period of time to be useful for the purposes detailed herein.

The term “microorganism” or “microbe” as used herein includes, but is not limited to, bacteria, fungi, protozoa, yeast, mold, and mildew. The term “antimicrobial agent” as used herein refers to, but is not limited to, compounds capable of inhibiting, reducing or preventing growth of a microorganism, capable of inhibiting or reducing ability of a microorganism to produce infection in a host, or capable of inhibiting or reducing ability of a microorganism to multiply or remain infective in the environment. The term “antimicrobial agent” also refers to compounds capable of decreasing infectivity or virulence of a microorganism. In some embodiments, antimicrobial agent as used herein includes, but is not limited to, antibiotic agent, antibacterial agent, and antifungal agent.

In some embodiments, the terms “antibacterial agent” or “antibiotic agent” as used herein refers to compounds capable of inhibiting, reducing, or preventing growth of bacteria, capable of inhibiting or reducing ability of bacteria to produce infection in a host, or capable of inhibiting or reducing ability of bacteria to multiply or remain infective in the environment. The term “antibacterial agent” also refers to compounds capable of decreasing infectivity or virulence of bacteria.

In some embodiments, the term “antifungal agent” as used herein refers to compounds capable of inhibiting, reducing, or preventing growth of fungi, capable of inhibiting or reducing ability of fungi to produce infection in a host, or capable of inhibiting or reducing ability of fungi to grow or remain infective in the environment. The term “antifungal agent” also refers to compounds capable of decreasing infectivity of fungi.

In some embodiments, the term “growth” as used herein refers to the growth of microorganisms and includes reproduction or population expansion of the microorganism. The term also includes maintenance of on-going metabolic processes of a microorganism, including processes that keep the microorganism alive.

In some embodiments, the term “synergistic” or “synergy” as used herein refers to the interaction of two or more agents so that their combined effect is greater than their individual effects. In some embodiments, the term “potentiator” refer to a compound that, when co-administered with an antimicrobial agent, results in the overall increase of the anti-microbial activities. In some embodiments, the resulting anti-microbial activities are more potent, or significantly more potent, than the combined anti-microbial activities of the potentiator and the antimicrobial agent when administered separately. In some embodiments, the terms potentiator and adjuvant are used interchangeably.

Compounds

In some embodiments, compounds having the indole core form the base of a wide variety of natural and synthetic molecules with a plethora of biological activities. In particular bis(indolyl)methanes (BIMs) have been shown to possess antibacterial, antifungal, anti-HIV, and antitumor activities. BIMs are a large group of alkaloids with two indol-3-yl groups bridged by a single carbon. Naturally, BIMs are found in many marine and terrestrial organisms, though scientists have devised several methods of synthesizing BIM derivatives through facile, one-pot techniques.

In some embodiments, the compounds disclosed herein are antimicrobial adjuvants or potentiators.

In one aspect, the present disclosure provides a compound having Formula A or B,

where

each occurrence of R₉ is independently selected from the group consisting of NH₂, OH, CHO, NO₂, halogen, and (C₁ to C₆)alkyl optionally substituted with one or more of halogen, OH, NH₂, NO₂, or CHO; and where R₉ is substituted on the phenyl ring of Formula A or the imidazole ring of Formula B;

m is 0 to 5;

each occurrence of R₁₀ is independently H, halogen, OH, CN, NO₂, OCF₃, (C₁ to C₆)alkyl, (C₂ to C₆)alkenyl, (C₂ to C₆)alkynyl, (C₁ to C₆)alkoxy, (C₃ to C₇)cycloalkyl, 3-7-membered heterocycle, (C₁ to C₆) alkylthio, NR_(a)R_(b), (C₁ to C₆)haloalkyl, (CH₂)_(p)(C₃ to C₇)cycloalkyl, (CH₂)_(p)OR_(a), (CH₂)_(p)SR_(a), (CH₂)_(p)NR_(a)R_(b), (CH₂)_(p)(C₁ to C₆)haloalkyl, or CH(indole)₂, in which said heterocycle includes at least one heteroatom selected from the group consisting of nitrogen, oxygen, and sulfur and may be optionally substituted by from one to three groups which may be the same or different selected from the group consisting of halogen, OH, CN, (C₁ to C₄)alkyl, (C₁ to C₄)haloalkyl, and (C₁ to C₄)alkoxy, or alternatively two R₁₀ taken together with the ring atoms that they are connected to form a 4-7-membered aromatic ring; where R₁₀ is substituted on the indole ring and/or the phenyl ring of Formula A or on the imidazole ring of Formula B;

each of n, o, p, and q is independently an integer from 0 to 4; R₇ and R₈ are each independently H, halogen, OH, CN, OCF₃, (C₁ to C₆)alkyl, (C₂ to C₆)alkenyl, (C₂ to C₆)alkynyl, (C₁ to C₆)alkoxy, (C₃ to C₇)cycloalkyl, 3-7-membered heterocycle, (C₁ to C₆)alkylthio, NR_(a)R_(b), (C₁ to C₆)haloalkyl, (CH₂)_(p)(C₃ to C₇)cycloalkyl, (CH₂)_(p)OR_(a), (CH₂)_(p)SR_(a), (CH₂)_(p)NR_(a)R_(b), or (CH₂)_(p)(C₁ to C₆)haloalkyl, in which said heterocycle contains at least one heteroatom selected from the group consisting of nitrogen, oxygen and sulfur and may be optionally substituted by from one to three groups which may be the same or different selected from the group consisting of halogen, OH, CN, (C₁ to C₄)alkyl, (C₁ to C₄)haloalkyl, and (C₁ to C₄)alkoxy;

R_(a) and R_(b) are each independently H, (C₁ to C₆)alkyl, (C₂ to C₆)alkenyl, or (C₃ to C₇)cycloalkyl;

each occurrence of R₁₁ is independently H, halogen, OH, CN, NO₂, OCF₃, (C₁ to C₆) alkyl, (C₂ to C₆)alkenyl, (C₂ to C₆)alkynyl, (C₁ to C₆)alkoxy, (C₃ to C₇)cycloalkyl, 3-7-membered heterocycle, (C₁ to C₆)alkylthio, NR_(a)R_(b), (C₁ to C₆)haloalkyl, (CH₂)_(p)(C₃ to C₇)cycloalkyl, (CH₂)_(p)OR_(a), (CH₂)_(p)SR_(a), or (CH₂)_(p)NR_(a)R_(b), in which said heterocycle includes at least one heteroatom selected from the group consisting of nitrogen, oxygen and sulfur and may be optionally substituted by from one to three groups which may be the same or different selected from the group consisting of halogen, OH, CN, (C₁ to C₄)alkyl, (C₁ to C₄)haloalkyl and (C₁ to C₄)alkoxy;

R_(a) and R_(b) are each independently H, (C₁ to C₆) alkyl, (C₂ to C₆) alkenyl, or (C₃ to C₇) cycloalkyl; and

x is optionally present, where x is a positive charge.

In another aspect, the present disclosure provides a pharmaceutical composition, including an antimicrobial agent and a compound having Formula A or B,

where

each occurrence of R₉ is independently selected from the group consisting of NH₂, NO₂, OH, CHO, halogen, and C₁ to C₆ alkyl optionally substituted with one or more of halogen, OH, NH₂, NO₂, or CHO; and where R₉ is substituted on the phenyl ring of Formula A or the imidazole ring of Formula B;

m is 0 to 5;

each occurrence of R₁₀ is independently H, halogen, OH, CN, NO₂, OCF₃, (C₁ to C₆)alkyl, (C₂ to C₆)alkenyl, (C₂ to C₆)alkynyl, (C₁ to C₆)alkoxy, (C₃ to C₇)cycloalkyl, 3-7-membered heterocycle, (C₁ to C₆)alkylthio, NR_(a)R_(b), (C₁ to C₆)haloalkyl, (CH₂)_(p)(C₃ to C₇)cycloalkyl, (CH₂)_(p)OR_(a), (CH₂)_(p)SR_(a), (CH₂)_(p)NR_(a)R_(b), (CH₂)_(p)(C₁ to C₆)haloalkyl, or CH(indole)₂, in which said heterocycle includes at least one heteroatom selected from the group consisting of nitrogen, oxygen, and sulfur and may be optionally substituted by from one to three groups which may be the same or different selected from the group consisting of halogen, OH, CN, (C₁ to C₄)alkyl, (C₁ to C₄)haloalkyl, and (C₁ to C₄)alkoxy, or alternatively two R₁₀ taken together with the ring atoms that they are connected to form a 4-7-membered aromatic ring; where R₁₀ is a group substituted on the indole ring and/or the phenyl ring of Formula A or on the indole ring and/or the imidazole ring of Formula B;

each of n, o, p, and q is independently an integer from 0 to 4;

R₇ and R₈ are each independently H, halogen, OH, CN, OCF₃, (C₁ to C₆)alkyl, (C₂ to C₆)alkenyl, (C₂ to C₆)alkynyl, (C₁ to C₆)alkoxy, (C₃ to C₇)cycloalkyl, 3-7-membered heterocycle, (C₁ to C₆)alkylthio, NR_(a)R_(b), (C₁ to C₆)haloalkyl, (CH₂)_(p)(C₃ to C₇)cycloalkyl, (CH₂)_(p)OR_(a), (CH₂)_(p)SR_(a), (CH₂)_(p)NR_(a)R_(b), or (CH₂)_(p)(C₁ to C₆)haloalkyl, in which said heterocycle contains at least one heteroatom selected from the group consisting of nitrogen, oxygen and sulfur and may be optionally substituted by from one to three groups which may be the same or different selected from the group consisting of halogen, OH, CN, (C₁ to C₄)alkyl, (C₁ to C₄)haloalkyl and (C₁ to C₄)alkoxy;

each occurrence of R₁₁ is independently H, halogen, OH, CN, NO₂, OCF₃, (C₁ to C₆) alkyl, (C₂ to C₆)alkenyl, (C₂ to C₆)alkynyl, (C₁ to C₆)alkoxy, (C₃ to C₇)cycloalkyl, 3-7-membered heterocycle, (C₁ to C₆)alkylthio, NR_(a)R_(b), (C₁ to C₆)haloalkyl, (CH₂)_(p)(C₃ to C₇)cycloalkyl, (CH₂)_(p)OR_(a), (CH₂)_(p)SR_(a), or (CH₂)_(p)NR_(a)R_(b), in which said heterocycle includes at least one heteroatom selected from the group consisting of nitrogen, oxygen and sulfur and may be optionally substituted by from one to three groups which may be the same or different selected from the group consisting of halogen, OH, CN, (C₁ to C₄)alkyl, (C₁ to C₄)haloalkyl and (C₁ to C₄)alkoxy;

R_(a) and R_(b) are each independently H, (C₁ to C₆) alkyl, (C₂ to C₆) alkenyl, or (C₃ to C₇) cycloalkyl; and

x is optionally present, where x is a positive charge.

In certain embodiments, R₇ and R₈ are each independently H, halogen, OH, CN, OCF₃, (C₁ to C₆)alkyl, (C₂ to C₆)alkenyl, (C₂ to C₆)alkynyl, (C₁ to C₆)alkoxy, or (C₃ to C₇)cycloalkyl. In certain embodiments, R₇ and R₈ are each independently (C₁ to C₆)alkylthio, NR_(a)R_(b), (C₁ to C₆)haloalkyl, (CH₂)_(p)(C₃ to C₇)cycloalkyl, (CH₂)_(p)OR_(a), (CH₂)_(p)SR_(a), (CH₂)_(p)NR_(a)R_(b), or (CH₂)_(p)(C₁ to C₆)haloalkyl. In other embodiments, R₇ and R₈ are each independently 3 to 7-membered heterocycle optionally substituted by from one to three groups which may be the same or different selected from the group consisting of halogen, OH, CN, (C₁ to C₄)alkyl, (C₁ to C₄)haloalkyl, and (C₁ to C₄)alkoxy.

In certain embodiments, R₇ and R₈ are each independently OCH₃ or (C₂ to C₆)alkoxy. In certain embodiments, R₇ and R₈ are OCH₃. In certain embodiments, R₇ and R₈ are each independently H or (C₁ to C₆)alkyl. In certain embodiments, R₇ and R₈ are H.

In certain embodiments, R₇ and R₈ are independently Br or OH.

In certain embodiments, R₇ and R₈ are Br.

In certain embodiments, R₇ and R₈ are OH.

In certain embodiments, the compound has the structure of formula A′:

where the various substituents are as defined herein.

In certain embodiments, the compound has the structure of formula A″:

where the various substituents are as defined herein. In certain embodiments, the compound has the structure of formula A′″:

where the various substituents are as defined herein.

In certain embodiments, the compound has the structure of formula A1:

where the various substituents are as defined herein.

In certain embodiments, the compound has the structure of formula A2:

where the various substituents are as defined herein.

In certain embodiments, at least one R₉ is selected from the group consisting of NH₂, OH, CHO, and halogen. In certain embodiments, at least one R₉ is halogen or (C₁ to C₆)alkyl substituted with one or more of halogen. In certain embodiments, at least one R₉ is halogen. In certain embodiments, at least one R₉ is Cl or Br. In certain embodiments, at least one R₉ is F.

In certain embodiments, at least one R₉ is NH₂ or (C₁ to C₆)alkyl substituted with one or more of NH₂. In certain embodiments, at least one R₉ is NH₂. In certain embodiments, at least one R₉ is NO₂. In certain embodiments, at least one R₉ is CHO or (C₁ to C₆)alkyl substituted with one or more of CHO. In certain embodiments, at least one R₉ is OH or (C₁ to C₆)alkyl substituted with one or more of OH. In certain embodiments, at least one R₉ is OH.

In certain embodiments, each R₉ is independently selected from the group consisting of CH₃, OH, NH₂, NO₂, CHO, and C(CH₃)₃.

In certain embodiments, each R₁₀ is independently selected from the group consisting of halogen, CH₃, N(CH₃)₂, NO₂, CHO, OH, OCH₃, NH₂, C(CH₃)₃, and

or where two R₁₀ taken together with the ring atoms they are connected to form a 6-membered aromatic ring.

In certain embodiments, each occurrence of R₁₀ is independently H, halogen, OH, CN, OCF₃, (C₁ to C₆)alkyl, (C₂ to C₆)alkenyl, (C₂ to C₆)alkynyl, (C₁ to C₆)alkoxy, or (C₃ to C₇)cycloalkyl. In certain embodiments, each occurrence of R₁₀ is independently 3-7-membered heterocycle, (C₁ to C₆)alkylthio, NR_(a)R_(b), (C₁ to C₆)haloalkyl, (CH₂)_(p)(C₃ to C₇)cycloalkyl, (CH₂)_(p)OR_(a), (CH₂)_(p)SR_(a), (CH₂)_(p)NR_(a)R_(b), or (CH₂)_(p)(C₁ to C₆)haloalkyl. In certain embodiments, each occurrence of R₁₀ is H. In certain embodiments, each occurrence of R₁₀ is independently H. In certain embodiments, each occurrence of R₁₀ is independently F. In certain embodiments, each occurrence of R₁₀ is independently C₁. In certain embodiments, each occurrence of R₁₀ is independently Br. In certain embodiments, each occurrence of R₁₀ is independently OH. In certain embodiments, each occurrence of R₁₀ is independently NH₂.

In some embodiments, R₁₁ is H, halogen, OH, CN, NO₂, OCF₃, (C₁ to C₆)alkyl, (C₂ to C₆)alkenyl, (C₂ to C₆)alkynyl, (C₁ to C₆)alkoxy, (C₃ to C₇)cycloalkyl, (CH₂)_(p)(3-7-membered heterocycle), (C₁ to C₆)alkylthio, NR_(a)R_(b), (C₁ to C₆)haloalkyl, (CH₂)_(p)(C₃ to C₇)cycloalkyl, (CH₂)_(p)OR_(a), (CH₂)_(p)SR_(a), (CH₂)_(p)NR_(a)R_(b), or (CH₂)_(p)(C₁ to C₆)haloalkyl, in which said heterocycle includes at least one heteroatom selected from the group consisting of nitrogen, oxygen and sulfur and may be optionally substituted by from one to three groups which may be the same or different selected from the group consisting of halogen, OH, CN, (C₁ to C₄)alkyl, (C₁ to C₄)haloalkyl, and (C₁ to C₄)alkoxy.

In some embodiments, R₁₁ is (C₁ to C₆)alkyl, (C₁ to C₆)alkoxy, or OH. In some embodiments, R₁₁ is methyl, ethyl, propyl, or butyl. In certain embodiments, R₁₁ is methyl. In certain embodiments, R₁₁ is ethyl. In certain embodiments, R₁₁ is methyl. In certain embodiments, R₁₁ is n-propyl or iso-propyl. In some embodiments, R₁₁ is OH, OCH₃, OCH₂CH₃, or O(CH₂)₂CH₃. In certain embodiments, R₁₁ is OH. In certain embodiments, Ru is OCH₃.

In certain embodiments, R_(a) and R_(b) are each independently H, C₁ to C₆ alkyl, C₂ to C₆ alkenyl, or C₃ to C₇ cycloalkyl. In certain embodiments, at least one of R_(a) and R_(b) is H. In certain embodiments, at least one of R_(a) and R_(b) is Me, Et, or propyl. In certain embodiments, at least one of R_(a) and R_(b) is cyclopropyl or cyclobutyl. In certain embodiments, both R_(a) and R_(b) are H.

In certain embodiments, o is 0, 1, 2, 3, or 4. In certain embodiments, o is 0. In certain embodiments, o is 1. In certain embodiments, o is 2. In certain embodiments, o is 3. In certain embodiments, o is 4. In certain embodiments, o and q are each independently 0, 1 or 2. In certain embodiments, o and q are 0. In certain embodiments, m is 0. In certain embodiments, m is 1, 2, or 3. In certain embodiments, m is 1. In certain embodiments, m is 2. In certain embodiments, n is 1 or 2. In certain embodiments, n is 3 or 4. In certain embodiments, n is 0. In certain embodiments, q is 0, 1, 2, 3, or 4. In certain embodiments, q is 0. In certain embodiments, q is 1. In certain embodiments, q is 2. In certain embodiments, q is 3. In certain embodiments, q is 4. In certain embodiments, p is 0, 1, 2, 3, or 4. In certain embodiments, p is 0. In certain embodiments, p is 1. In certain embodiments, p is 2. In certain embodiments, p is 3. In certain embodiments, p is 4.

In certain embodiments, x is not present and the compound as disclosed is neutral. In certain embodiments, x is present as a positive charge and the compound as disclosed further includes a counterion. In certain embodiments, the counterion is an organic or inorganic anion. In certain embodiments, the counterion is F⁻, Cl⁻, Br⁻, I⁻, HCO₃ ⁻, and CF₃COO⁻, and CF₃O₃S⁻.

In certain embodiments, the present disclosure provides a compound selected from the group consisting of

In certain embodiments, the present disclosure provides a compound selected from the group consisting of

In certain embodiments, the present disclosure provides a compound of Formula:

In certain embodiments, the present disclosure provides a compound of Formula:

In another aspect, the present disclosure provides a pharmaceutical composition including compounds as described herein and pharmaceutically acceptable excipients. In some embodiments, the pharmaceutical composition further includes an antimicrobial agent. In certain embodiments, the antimicrobial agent is an antibacterial agent.

In some embodiments, the antimicrobial agent is an antifungal agent. In some embodiments, the antimicrobial agent is a macrolide, a folic acid synthesis inhibitor, a fluoroquinolone, an aminoglycoside, a monobactam, a cephalosporin, a glycopeptide, a β-lactam, a carbapenem, or a tetracycline.

In certain embodiments, the present disclosure provides a pharmaceutical composition as described herein, where the antimicrobial agent is selected from the group of ampicillin, imipenem, cephalexin, erythromycin, aztreonam, trimethoprim, streptomycin, ciprofloxacin, vancomycin, doxycycline, and kanamycin.

In certain embodiments, the present disclosure provides a pharmaceutical composition as described herein, including

and an antimicrobial agent selected from the group consisting of ampicillin, imipenem, cephalexin, erythromycin, streptomycin, vancomycin, doxycycline, and kanamycin.

In certain embodiments, the present disclosure provides a pharmaceutical composition as described herein, including

and an antimicrobial agent selected from the group consisting of ampicillin, imipenem, cephalexin, aztreonam, trimethoprim, streptomycin, ciprofloxacin, vancomycin, doxycycline, and kanamycin.

In certain embodiments, the present disclosure provides a pharmaceutical composition as described herein, including

and an antimicrobial agent selected from the group of ampicillin, imipenem, cephalexin, erythromycin, aztreonam, trimethoprim, streptomycin, ciprofloxacin, vancomycin, doxycycline, and kanamycin.

In certain embodiments, the present disclosure provides a pharmaceutical composition as described herein, including

and an antimicrobial agent selected from the group of ampicillin, imipenem, cephalexin, erythromycin, aztreonam, trimethoprim, streptomycin, ciprofloxacin, vancomycin, doxycycline, and kanamycin.

In certain embodiments, the present disclosure provides a pharmaceutical composition as described herein, including

and an antimicrobial agent selected from the group of ampicillin, imipenem, cephalexin, aztreonam, trimethoprim, streptomycin, ciprofloxacin, vancomycin, doxycycline, and kanamycin.

Utility and Methods of Use

In another aspect, the present disclosure provides a method of treating, preventing, or reducing the risk of a microbial infection in a patient, the method including administering a compound of Formula A or B described herein, or a pharmaceutical composition thereof. In another aspect, the present disclosure provides a method of treating, preventing, or reducing the risk of a microbial infection in a patient, the method including administering an antimicrobial agent and a compound of Formula A or B described herein.

In another aspect, the present disclosure provides a method of treating, preventing, or reducing the risk of a microbial infection in a patient, the method including administering the pharmaceutical composition described herein.

In certain embodiments, the method includes treating, preventing, or reducing the risk of biofilms, hemotoxicity, and/or virulence of a microbial infection.

In certain embodiments, the microbial infection includes one or more bacteria, yeast, fungi, or combinations thereof. In certain embodiments, the microbial infection includes one or more bacteria. In certain embodiments, the microbial infection includes one or more yeast. In certain embodiments, the microbial infection includes one or more fungi.

In certain embodiments, the administration is performed once daily.

In certain embodiments, the microbes are clinically antibiotic resistant.

In certain embodiments, the microbes form biofilms.

In another aspect, the present disclosure provides a method of inhibiting or extinguishing the growth of one or more microbial cultures in vitro, the method including administering an antimicrobial agent and a compound as described herein.

In a further another aspect, the present disclosure provides a method of inhibiting or extinguishing the growth, virulence, or hemotoxicity of one or more microbial cultures in vitro, the method including administering an antimicrobial agent and a compound or the pharmaceutical composition as described herein.

In a further another aspect, the present disclosure provides a method of reducing the expression of bacterial genes promoting resistance of the bacterial cells to antibiotics, the method including administering a compound or the pharmaceutical composition as described herein.

In some embodiments, the present disclosure provides a method of reducing the expression of bacterial genes promoting virulence of the bacterial cells and their resistance to antibiotics as described herein, the method including administering a compound or the pharmaceutical composition as described herein, where an antimicrobial agent is also administered to the bacterial cells.

In some embodiments, the bacterial genes promoting virulence of the bacterial cells and their resistance to antibiotics include mecA, blaZ, and fnbA.

In a further another aspect, the present disclosure provides a method of reducing of global regulator genes in bacterial cells, the method including administering a compound or the pharmaceutical composition as described herein.

In some embodiments, an antimicrobial agent is also administered to the bacterial cells.

In some embodiments, the global regulator genes include sarA, agrA, and RNA III.

In certain embodiments, the present disclosure provides a method as described herein, where the antimicrobial agent is a macrolide, a folic acid synthesis inhibitor, a fluoroquinolone, an aminoglycoside, a monobactam, a cephalosporin, a glycopeptide, a β-lactam, a carbapenem, or a tetracycline.

In certain embodiments, the present disclosure provides a method as described herein, where the antimicrobial agent is selected from the group consisting of erythromycin, trimethoprim, ciprofloxacin, streptomycin, aztreonam, cefalexin, vancomycin, ampicillin, doxycycline, and kanamycin.

In certain embodiments, the present disclosure provides a method as described herein, where the antimicrobial agent is selected from the group of vancomycin and ampicillin.

In certain embodiments, the microbe is Gram-positive bacteria.

In certain embodiments, the microbe is Gram-negative bacteria.

In certain embodiments, the microbe is a mixture of both Gram-positive and Gram-negative bacteria.

In certain embodiments, the microbe is selected from the group consisting of Bacillus cereus, Streptococcus pyogenes, Streptococcus pneumoniae, Staphylococcus aureus, Enterococcus faecium, Corynebacterium diphtheriae, Escherichia coli, Salmonella typhimurium, Pseudomonas aeruginosa, Klebsiella pneumoniae, Candida albicans, and mixtures thereof.

In certain embodiments, the microbe is selected from the group consisting of Staphylococcus aureus, Streptococcus pneumoniae, Klebsiella pneumoniae Escherichia coli, and a combination thereof.

In certain embodiments, the microbe is Staphylococcus aureus, Enterococcus faecium, or a mixture thereof.

In certain embodiments, the microbe is Staphylococcus aureus.

In certain embodiments, the microbe is MRSA.

Pharmaceutical Compositions

This disclosure also provides a pharmaceutical composition including at least one of the compounds as described herein or a pharmaceutically acceptable salt thereof, optionally an antibiotic agent, and a pharmaceutically acceptable carrier.

The phrase “pharmaceutically-acceptable carrier” as used herein means a pharmaceutically-acceptable material, composition or vehicle, such as a liquid or solid filler, diluent, excipient, solvent or encapsulating material, involved in carrying or transporting the subject pharmaceutical agent from one organ, or portion of the body, to another organ, or portion of the body. Each carrier must be “acceptable” in the sense of being compatible with the other ingredients of the formulation and not injurious to the patient. Some examples of materials which can serve as pharmaceutically-acceptable carriers include, but are not limited to: sugars, such as lactose, glucose, and sucrose; starches, such as corn starch and potato starch; cellulose and its derivatives, such as sodium carboxymethyl cellulose, ethyl cellulose, and cellulose acetate; powdered tragacanth; malt; gelatin; talc; excipients, such as cocoa butter and suppository waxes; oils, such as peanut oil, cottonseed oil, safflower oil, sesame oil, olive oil, corn oil, and soybean oil; glycols, such as butylene glycol; polyols, such as glycerin, sorbitol, mannitol, and polyethylene glycol; esters, such as ethyl oleate and ethyl laurate; agar; buffering agents, such as magnesium hydroxide and aluminum hydroxide; alginic acid; pyrogen-free water; isotonic saline; Ringer's solution; ethyl alcohol; phosphate buffer solutions; and other non-toxic compatible substances employed in pharmaceutical formulations.

As set out above, certain embodiments of the present pharmaceutical agents may be provided in the form of pharmaceutically acceptable salts. The term “pharmaceutically-acceptable salt”, in this respect, refers to the relatively non-toxic, inorganic and organic acid addition salts of compounds of the present disclosure. These salts can be prepared in situ during the final isolation and purification of the compounds of the disclosure, or by separately reacting a purified compound of the disclosure in its free base form with a suitable organic or inorganic acid, and isolating the salt thus formed. Representative salts include, but are not limited to, the hydrobromide, hydrochloride, sulfate, bisulfate, phosphate, nitrate, acetate, valerate, oleate, palmitate, stearate, laurate, benzoate, lactate, phosphate, tosylate, citrate, maleate, fumarate, succinate, tartrate, naphthylate, mesylate, glucoheptonate, lactobionate, and laurylsulphonate salts, and the like. (See, for example, Berge et al., (1977) “Pharmaceutical Salts”, J. Pharm. Sci. 66:1-19).

The pharmaceutically acceptable salts of the subject compounds include the conventional nontoxic salts or quaternary ammonium salts of the compounds, e.g., from non-toxic organic or inorganic acids. For example, such conventional nontoxic salts include those derived from inorganic acids such as hydrochloride, hydrobromic, sulfuric, sulfamic, phosphoric, nitric, and the like; and the salts prepared from organic acids such as acetic, butionic, succinic, glycolic, stearic, lactic, malic, tartaric, citric, ascorbic, palmitic, maleic, hydroxymaleic, phenylacetic, glutamic, benzoic, salicylic, sulfanilic, 2-acetoxybenzoic, fumaric, toluenesulfonic, methanesulfonic, ethane disulfonic, oxalic, isothionic, and the like.

In other cases, the compounds of the present disclosure may contain one or more acidic functional groups and, thus, are capable of forming pharmaceutically acceptable salts with pharmaceutically acceptable bases. The term “pharmaceutically-acceptable salts” in these instances refers to the relatively non-toxic, inorganic and organic base addition salts of compounds of the present disclosure. These salts can likewise be prepared in situ during the final isolation and purification of the compounds, or by separately reacting the purified compound in its free acid form with a suitable base, such as the hydroxide, carbonate, or bicarbonate of a pharmaceutically-acceptable metal cation, with ammonia, or with a pharmaceutically-acceptable organic primary, secondary, or tertiary amine. Representative alkali or alkaline earth salts include the lithium, sodium, potassium, calcium, magnesium, and aluminum salts, and the like. Representative organic amines useful for the formation of base addition salts include ethylamine, diethylamine, ethylenediamine, ethanolamine, diethanolamine, piperazine, and the like. (See, for example, Berge et al., supra)

Wetting agents, emulsifiers, and lubricants, such as sodium lauryl sulfate, magnesium stearate, and polyethylene oxide-polybutylene oxide copolymer, as well as coloring agents, release agents, coating agents, sweetening, flavoring, and perfuming agents, preservatives, and antioxidants, can also be present in the compositions.

Formulations of the present disclosure include those suitable for oral, nasal, topical (including buccal and sublingual), rectal, vaginal, and/or parenteral administration. The formulations may conveniently be presented in unit dosage form and may be prepared by any methods well known in the art of pharmacy. The amount of active ingredient which can be combined with a carrier material to produce a single dosage form will vary depending upon the host being treated and the particular mode of administration. The amount of active ingredient, which can be combined with a carrier material to produce a single dosage form will generally be that amount of the compound which produces a therapeutic effect. Generally, out of 100%, this amount will range from about 1% to about 99% of active ingredient, preferably from about 5% to about 70%, most preferably from about 10% to about 30%.

Methods of preparing these formulations or compositions include the step of bringing into association a compound of the present disclosure with the carrier and, optionally, one or more accessory ingredients. In general, the formulations are prepared by uniformly and intimately bringing into association a compound of the present disclosure with liquid carriers, or finely divided solid carriers, or both, and then, if necessary, shaping the product.

Formulations of the disclosure suitable for oral administration may be in the form of capsules, cachets, pills, tablets, lozenges (using a flavored basis, usually sucrose and acacia or tragacanth), powders, granules, or as a solution or a suspension in an aqueous or nonaqueous liquid, or as an oil-in-water or water-in-oil liquid emulsion, or as an elixir or syrup, or as pastilles (using an inert base, such as gelatin and glycerin, or sucrose and acacia), and/or as mouth washes, and the like, each containing a predetermined amount of a compound of the present disclosure as an active ingredient. A compound disclosed herein may also be administered as a bolus, electuary, or paste.

In solid dosage forms of the disclosure for oral administration (capsules, tablets, pills, dragees, powders, granules, and the like), the active ingredient is mixed with one or more pharmaceutically-acceptable carriers, such as sodium citrate or dicalcium phosphate, and/or any of the following: fillers or extenders, such as starches, lactose, sucrose, glucose, mannitol, and/or silicic acid; binders, such as, for example, carboxymethylcellulose, alginates, gelatin, polyvinyl pyrrolidone, sucrose, and/or acacia; humectants, such as glycerol; disintegrating agents, such as agar-agar, calcium carbonate, potato or tapioca starch, alginic acid, certain silicates, sodium carbonate, and sodium starch glycolate; solution retarding agents, such as paraffin; absorption accelerators, such as quaternary ammonium compounds; wetting agents, such as, for example, cetyl alcohol, glycerol monostearate, and polyethylene oxide-polybutylene oxide copolymer; absorbents, such as kaolin and bentonite clay; lubricants, such a talc, calcium stearate, magnesium stearate, solid polyethylene glycols, sodium lauryl sulfate, and mixtures thereof; and coloring agents. In the case of capsules, tablets, and pills, the pharmaceutical compositions may also include buffering agents. Solid compositions of a similar type may also be employed as fillers in soft and hard-filled gelatin capsules using such excipients as lactose or milk sugars, as well as high molecular weight polyethylene glycols and the like.

A tablet may be made by compression or molding, optionally with one or more accessory ingredients. Compressed tablets may be prepared using binder (for example, gelatin or hydroxybutylmethyl cellulose), lubricant, inert diluent, preservative, disintegrant (for example, sodium starch glycolate or cross-linked sodium carboxymethyl cellulose), surface-active, or dispersing agent. Molded tablets, may be, made by molding in a suitable machine a mixture of the powdered compound moistened with an inert liquid diluent.

The tablets, and other solid dosage forms of the pharmaceutical compositions of the present disclosure, such as dragees, capsules, pills, and granules, may optionally be scored or prepared with coatings and shells, such as enteric coatings and other coatings well known in the pharmaceutical-formulating art. They may also be formulated so as to provide slow or controlled release of the active ingredient therein using, for example, hydroxybutylmethyl cellulose in varying butortions to provide the desired release profile, other polymer matrices, liposomes, and/or microspheres. They may be sterilized by, for example, filtration through a bacteria-retaining filter, or by incorporating sterilizing agents in the form of sterile solid compositions, which can be dissolved in sterile water, or some other sterile injectable medium, immediately before use. These compositions may also optionally contain opacifying agents and may be of a composition that they release the active ingredient(s) only, or preferentially, in a certain portion of the gastrointestinal tract, optionally, in a delayed manner. Examples are embedding compositions, which can be used include polymeric substances and waxes. The active ingredient can also be in micro-encapsulated form, if apbutriate, with one or more of the above-described excipients.

Liquid dosage forms for oral administration of the compounds disclosed herein include pharmaceutically acceptable emulsions, microemulsions, solutions, suspensions, syrups, and elixirs. In addition to the active ingredient, the liquid dosage forms may contain inert diluents commonly used in the art, such as, for example, water or other solvents, solubilizing agents and emulsifiers, such as ethyl alcohol, isobutyl alcohol, ethyl carbonate, ethyl acetate, benzyl alcohol, benzyl benzoate, butylene glycol, 1,3-butylene glycol, oils (in particular, cottonseed, groundnut, corn, germ, olive, castor, and sesame oils), glycerol, tetrahydrofuryl alcohol, polyethylene glycols, and fatty acid esters of sorbitan, and mixtures thereof. Additionally, cyclodextrins, e.g., hydroxybutyl-β-cyclodextrin, may be used to solubilize compounds.

Besides inert diluents, the oral compositions can also include adjuvants such as wetting agents, emulsifying and suspending agents, sweetening, flavoring, coloring, perfuming, and preservative agents.

Suspensions, in addition to the active compounds, may contain suspending agents as, for example, ethoxylated isostearyl alcohols, polyoxyethylene sorbitol and sorbitan esters, microcrystalline cellulose, aluminum metahydroxide, bentonite, agar-agar, and tragacanth, and mixtures thereof.

Formulations of the pharmaceutical compositions disclosed herein for rectal or vaginal administration may be presented as a suppository, which may be prepared by mixing one or more compounds disclosed herein with one or more suitable nonirritating excipients or carriers including, for example, cocoa butter, polyethylene glycol, a suppository wax, or a salicylate, and which is solid at room temperature, but liquid at body temperature and, therefore, will melt in the rectum or vaginal cavity and release the active pharmaceutical agents disclosed herein.

Formulations disclosed herein which are suitable for vaginal administration also include pessaries, tampons, creams, gels, pastes, foams, or spray formulations containing such carriers as are known in the art to be apbutriate.

Dosage forms for the topical or transdermal administration of a compound disclosed herein include powders, sprays, ointments, pastes, creams, lotions, gels, solutions, patches, and inhalants. The active compound may be mixed under sterile conditions with a pharmaceutically acceptable carrier, and with any preservatives, buffers, or butellants which may be required.

The ointments, pastes, creams, and gels may contain, in addition to an active compound as disclosed herein, excipients, such as animal and vegetable fats, oils, waxes, paraffins, starch, tragacanth, cellulose derivatives, polyethylene glycols, silicones, bentonites, silicic acid, talc, and zinc oxide, or mixtures thereof.

Powders and sprays can contain, in addition to a compound as disclosed herein, excipients such as lactose, talc, silicic acid, aluminum hydroxide, calcium silicates, and polyamide powder, or mixtures of these substances. Sprays can additionally contain customary butellants, such as chlorofluorohydrocarbons and volatile unsubstituted hydrocarbons, such as butane.

Transdermal patches have the added advantage of providing controlled delivery of a compound as disclosed herein to the body. Such dosage forms can be made by dissolving, or dispersing the pharmaceutical agents in the buter medium. Absorption enhancers can also be used to increase the flux of the pharmaceutical agents disclosed herein across the skin. The rate of such flux can be controlled, by either providing a rate controlling membrane or dispersing the compound in a polymer matrix or gel.

Ophthalmic formulations, eye ointments, powders, solutions, and the like, are also contemplated as being within the scope of this disclosure.

Pharmaceutical compositions as disclosed herein suitable for parenteral administration include one or more compounds as disclosed herein in combination with one or more pharmaceutically-acceptable sterile isotonic aqueous or nonaqueous solutions, dispersions, suspensions or emulsions, or sterile powders which may be reconstituted into sterile injectable solutions or dispersions just prior to use, which may contain antioxidants, buffers, bacteriostats, solutes which render the formulation isotonic with the blood of the intended recipient, or suspending or thickening agents.

In some cases, in order to prolong the effect of a drug, it is desirable to slow the absorption of the drug from subcutaneous or intramuscular injection. This may be accomplished by the use of a liquid suspension of crystalline or amorphous material having poor water solubility. The rate of absorption of the drug then depends upon its rate of dissolution, which, in turn, may depend upon crystal size and crystalline form. Alternatively, delayed absorption of a parenterally administered drug form is accomplished by dissolving or suspending the drug in an oil vehicle. One strategy for depot injections includes the use of polyethylene oxide-polybutylene oxide copolymers where the vehicle is fluid at room temperature and solidifies at body temperature.

Injectable depot forms are made by forming microencapsule matrices of the subject compounds in biodegradable polymers such as polylactide-polyglycolide. Depending on the ratio of drug to polymer, and the nature of the particular polymer employed, the rate of drug release can be controlled. Examples of other biodegradable polymers include poly (orthoesters) and poly (anhydrides). Depot injectable formulations are also prepared by entrapping the drug in liposomes or microemulsions, which are compatible with body tissue.

When the compounds disclosed herein are administered as pharmaceuticals, to humans and animals, they can be given per se or as a pharmaceutical composition containing, for example, 0.1% to 99.5% (more preferably, 0.5% to 90%) of active ingredient in combination with a pharmaceutically acceptable carrier.

The compounds and pharmaceutical compositions disclosed herein can be employed in combination therapies, that is, the compounds and pharmaceutical compositions can be administered concurrently with, prior to, or subsequent to, one or more other desired therapeutics or medical procedures. The particular combination of therapies (therapeutics or procedures) to employ in a combination regimen will take into account compatibility of the desired therapeutics and/or procedures and the desired therapeutic effect to be achieved. It will also be appreciated that the therapies employed may achieve a desired effect for the same disorder (for example, the compound as disclosed herein may be administered concurrently with another anti-HCV agent), or they may achieve different effects (e.g., control of any adverse effects).

The compounds disclosed herein may be administered intravenously, intramuscularly, intraperitoneally, subcutaneously, topically, orally, or by other acceptable means. The compounds may be used to treat arthritic conditions in mammals (i.e., humans, livestock, and domestic animals), birds, lizards, and any other organism, which can tolerate the compounds.

The disclosure also provides a pharmaceutical pack or kit including one or more containers filled with one or more of the ingredients of the pharmaceutical compositions disclosed herein. Optionally associated with such container(s) can be a notice in the form prescribed by a governmental agency regulating the manufacture, use or sale of pharmaceuticals or biological products, which notice reflects approval by the agency of manufacture, use or sale for human administration.

Methods of Synthesizing Compounds Described Herein

Due to the structure of the BIM skeleton, synthesis is accomplished using two molecules of indole and one carbonyl molecule with the use of an acid catalyst. The reaction of indole with aldehydes or ketones produces azafulvenium salts that react further with a second indole molecule to form the bis(indol-3-yl)methane. Further examples of the synthesis are described in more detail below.

EQUIVALENTS

The representative examples which follow are intended to help illustrate the disclosure, and are not intended to, nor should they be construed to, limit its scope. Indeed, various modifications of the disclosure and many further embodiments thereof, in addition to those shown and described herein, will become apparent to those skilled in the art from the full contents of this document, including the examples which follow and the references to the scientific and patent literature cited herein. It should further be appreciated that the contents of those cited references are incorporated herein by reference to help illustrate the state of the art. The following examples contain important additional information, exemplification, and guidance which can be adapted to the practice of this invention in its various embodiments and equivalents thereof.

EXAMPLES Example 1A: Substituted phenyl bis(indolyl)methanes (BIMs)

The representative substituted BIMs are listed in Table 1.

TABLE 1 Substituted phenyl bis(indolyl)methanes (BIMs) described in this application Indole Aldehyde Product Details

Name: bis(indol-3-yl)phenyl- methane Chemical Formula: C₂₃H₁₈N₂ Molecular Weight: 322.41 Yield: 89% Red amorphous solid TLC R_(f) (9:1 (v/v) CHCl₃: MeOH = 0.95

Name: [bis(indoly-3-yl)-4- dimethylaminophenyl]methane Chemical Formula: C₂₅H₂₃N₃ Molecular Weight: 365.48 Yield: 95% Purple amorphous solid

Name: [bis(indol-3-yl)-3,5-di- tert-butyl-2-hydroxyphenyl]- methane Chemical Formula: C₃₁H₃₄N₂O Molecular Weight: 450.63 Yield: 71%

Name: [bis(indol-3-yl)imidazol- 2-yl]methane Chemical Formula: C₂₀H₁₆N₄ Molecular Weight: 312.38 Yield: 20% White amorphous solid

Name: [bis(indol-3-yl)-3-nitro- phenyl]methane Chemical Formula: C₂₃H₁₇N₃O₂ Molecular Weight: 367.41 Yield: 98%

Name: [bis(indol-3-yl)-3- formylphenyl]methane Chemical Formula: C₂₄H₁₈N₂O Molecular Weight: 350.42 Yield: 40% TLC R_(f) ((6:4 (v/v) PE: EtOAc) = 0.05

Name: 1,3-bis[bis(indoly-3-yl)- methyl]benzene Chemical Formula: C₄₀H₃₀N₄ Molecular Weight: 566.71 Yield: 60% TLC R_(f) (6:4 (v/v) PE: EtOAc) = 0.13

Name: bis(indol-3-yl)-4-nitro- phenyl]methane Chemical Formula: C₂₃H₁₇N₃O₂ Molecular Weight: 367.41 Yield: 98% TLC R_(f) (3:2 (v/v) PE: EtOAc) = 0.175

Name: bis(indol-3-yl)-3- hydroxyphenyl Chemical Formula: C₂₃H₁₈N₂O Molecular Weight: 338.41 Yield: 93% TLC R_(f) (3:2 (v/v) PE: EtOAc) = 0.1

Name: bis(indol-3-yl)-4-amino- phenylmethane Chemical Formula: C₂₃H₁₉N₃ Molecular Weight: 337.43 Yield: 78%

Name: bis(indol-3-yl)-2- hydroxyphenylmethane Chemical Formula: C₂₃H₁₈N₂O Molecular Weight: 338.41 Yield: 56%

Name: bis(indol-3-yl)-2- methoxyphenylmethane Chemical Formula: C₂₄H₂₀N₂O Molecular Weight: 352.44 Yield: 49%

Name: bis(indol-3-yl)-2,3,5- trihydroxyphenylmethane Chemical Formula: C₂₃H₁₈N₂O₃ Molecular Weight: 370.41 Yield: 81% TLC R_(f) (9:1 (v/v) CHCl₃: MeOH) = 0.21

Name: bis[indol-3-yl)- phenanthren-9-ylmethane Chemical Formula: C₃₁H₂₂N₂ Molecular Weight: 422.53 Yield: 29%

Name: bis(indol-3-yl)-[4-bromo- 3-hydroxyphenyl]methane Chemical Formula: C₂₃H₁₇BrN₂O Molecular Weight: 417.31 Yield: 65%

Name: bis(indol-3-yl)-3-methyl- phenylmethane Chemical Formula: C₂₄H₂₀N₂ Molecular Weight: 336.44 Yield: 70%

Name: 4-bromo-2-hydroxy- phenylbis(indol-3-yl)methylium Chemical Formula: C₂₃H₁₆BrN₂O⁺ Molecular Weight: 416.30 Yield: 30%

Name: bis(indol-3-yl)-4- methoxyphenylmethane Chemical Formula: C₂₄H₂₀N₂O Molecular Weight: 352.44 Yield: 65%

Name: bis(6-methoxyindoly-3- yl)-3-hydroxyphenylmethane Chemical Formula: C₂₅H₂₂N₂O₃ Molecular Weight: 398.46 Yield: 90%

Name: bis(6-methoxyindol-3- yl)-4-nitrophenylmethane Chemical Formula: C₂₅H₂₁N₃O₄ Molecular Weight: 427.46 Yield: 95%

Name: 3,3′-((4-bromophenyl)- methylene)bis(6-bromo-1H indole) Chemical formula: C₂₃H₁₅Br₃N₂ Molecular weight: 559.0990 Yield: 72% TLC R_(f) (7:3 (v/v) PE: EtOAc) = 0.46

Name: 5-(bis(6-hydroxy-1H- indol-3-yl)methyl)benzene- 1,2,3-triol Chemical formula: C₂₃H₁₈N₂O₅ Molecular weight: 402.4060 Yield: 95%

Name: 3,3′-((4-bromophenyl)- methylene)bis(1H-indol-6-ol) Chemical formula: C₂₃H₁₇BrN₂O₂ Molecular weight: 433.3050 Yield: 89%

Name: 5-(bis(6-bromo-1H- indol-3-yl)methyl)benzene- 1,2,3-triol Chemical formula: C₂₃H₁₆Br₂N₂O₃ Molecular weight: 528.2000 Yield: 80%

Name: 3,3′-((3-bromophenyl)- methylene)bis(6-bromo-1H- indole) Chemical formula: C₂₃H₁₅Br₃N₂ Molecular weight: 559.0990 Yield: 91%

Name: 3,3′-((4-bromophenyl)- methylene)bis(1H-indol-5-ol) Chemical formula: C₂₃H₁₇BrN₂O₂ Molecular weight: 433.3050 Yield: 58%

Name: 5-(bis(5-hydroxy-1H- indol-3-yl)methyl)benzene- 1,2,3-triol Chemical formula: C₂₃H₁₈N₂O₅ Molecular weight: 402.4060 Yield: 67% TLC R_(f) (6:4 (v/v) PE:EtOAc, run twice) = 0.01

Name: 3,3′-((3-bromophenyl)- methylene)bis(1H-indol-5-ol) Chemical formula: C₂₃H₁₇BrN₂O₂ Molecular weight: 433.3050 Yield: 54% TLC R_(f) (8:2 (v/v) PE:EtOAc, run twice) = 0.05

Name: 3,3′-((3-bromophenyl)- methylene)bis(1H-indol-6-ol) Chemical formula: C₂₃H₁₇BrN₂O₂ Molecular weight: 433.3050 Yield: 77% TLC R_(f) (6:4 (v/v) PE:EtOAc, run twice) = 0.08

Example 1: Isolation, Synthesis and Derivatization of [bis(indol-3-yl)-phenyl]methane

Bis(Indol-3-yl)-phenylmethane (SP-BIM 1) was initially isolated from Pseudomonas aeruginosa strain UWI-1. All the SP-BIMs in this study were synthesized according to Schemes 1 and 2. Water was used as the protic solvent, but due to the insolubility of the indoles and aldehydes in this medium, a small amount (1%) of the surfactant sodium dodecyl sulfate (SDS) was added to the reaction as it forms micelles and solubilizes organic compounds.

To synthesize bis(indol-3-yl)-phenylmethane SP-BIM 1, indole (2 mmol) and benzaldehyde (1 mmol) were dissolved in 10 mL 1% SDS and stirred at room temperature for 6 hours. Two volumes of ethyl acetate were added to the reaction and stirred vigorously to extract the organic material. SDS was precipitated by the slow addition of CaCl₂) to the aqueous/organic mixture while vigorously stirring. The organic phase was collected and dried under reduced pressure and the product purified by gravity column chromatography using petroleum ether-ethyl acetate (6:4) as the eluent. The same method using various substituted benzaldehydes was used to synthesize the other SP-BIMs (Table 1).

SP-BIM 1 was initially isolated as an amorphous red solid and displayed antibiotic activity against only the Gram-positive organisms screened. Both ¹H and ¹³C NMR data compared well with literature data (Table 2), while the ESI mass spectrum showed a pseudomolecular ion at m/z 321.1363 [M+H]⁺ consistent with the molecular formula of [bis(indol-3-yl)-phenyl]methane, C₂₃H₁₈N₂. All SP-BIMs were successfully synthesized with relatively high yields (Table 1).

TABLE 2 Spectroscopic data for SP-BIM 1 in CDCl₃. HSQC Reference Spectra* Position ^(δ)H ^(δ)C ^(δ)H ^(δ)C 1 7.79 — 7.92 (brs, 2H) — 2 6.68 123.6 6.67 (s, 2H) 123.6 3 — 136.7 — 136.7  3a — 119.7 — 119.9 4 7.37 119.9 7.35-7.40 (m) 119.7 5 7.15 121.9 7.14-7.23 (m) 121.9 6 6.99 119.2 7.00 (t, J = 7.5 Hz, 2H) 119.2 7 7.30 111.0 7.35-7.40 (m) 111.0  7a — 127.0 — 127.0 8 5.86 40.20 5.89 (s, 1H) 40.20 9 — 144.0 — 144.1 10  7.32 128.7 7.35-7.40 (m) 128.7 11  7.26 128.2 7.24-7.30 (m, 2H) 128.2 12  7.20 126.1 7.14-7.23 (m) 126.1 *Hirashita et al., Bull. Chem. Soc. Japan 2015, 88: 1760-1764 was used as reference data.

Example 2: Antibacterial Activity of SP-BIMs

Reference microorganisms used in this study included: Bacillus cereus (American Type Culture Collection (ATCC) No. 14579), Streptococcus pyogenes (ATCC No. 19615), Staphylococcus aureus (ATCC No. 12600), Enterococcus faecium (ATCC No. 19434), Corynebacterium diphtheriae (ATCC No. 27010), Escherichia coli (ATCC No. 35218), Salmonella typhimurium (ATCC No. 14028), Pseudomonas aeruginosa (ATCC No. 27853), Klebsiella pneumoniae (ATCC No. 49472), and Candida albicans (ATCC No. 22972).

Clinical strains of MRSA (n=8) and Enterococcus faecium (n=10) were provided by the Department of Para-Clinical Sciences, University of the West Indies, St. Augustine, Trinidad. All bacterial cultures were cryopreserved in 30% glycerol/Brain Heart Infusion (BHI) at −80° C. Cultures were revived on BHI agar (Oxoid Ltd, Basingstoke, Hampshire, England) and maintained at 4° C. until needed.

Prior to each experiment, cultures were streaked onto clean BHI agar plates and incubated at 35° C. for 24 hours. Colonies of the respective cultures were selected and inoculated in phosphate buffer saline (pH 7.5) to a 0.5 McFarland turbidity standard (equivalent to 10⁸ CFU mL⁻¹). The bacterial suspension was then diluted 1:100 in cation adjusted Mueller Hinton Broth (ca-MHB) (Oxoid Ltd, Basingstoke, Hampshire, England).

Antibiotic powders and standard antibiotic discs were purchased from Himedia Ltd. (PA, USA). Antibiotic stock solutions were made at 50 mg mL⁻¹ according to Andrews, Antimicrob. Agents Chemother. 2001, 48:5-16 and working solutions were prepared 24 hours before needed and stored at 4° C.

Stock solutions (50 mg mL⁻¹) of the SP-BIM test compounds were prepared in DMSO and stored at 4° C. Working preparations of each compound was made up to 1 mg/mL in sterile deionized water with a final DMSO concentration of 10%.

To assess the antibiotic properties of the library of SP-BIMs, the broth microdilution assay was performed in 96-well microplates according to the Clinical and Laboratory Standards Institute 2014 Guidelines (CLSI 2014). The broth microdilution assay was used to determine the minimum inhibitory concentration (MIC). MIC represents the lowest concentration of the compound that would directly inhibit the growth of the pathogen. Bacterial cells (˜10⁶ CFU mL⁻¹) were inoculated into cation adjusted-Mueller Hinton broth containing the test compound in a twofold serial dilution ranging between 250 μg mL⁻¹ and 0.02 μg mL⁻¹. Plates were incubated at 35° C. for 18 hours after which 50 μL of 5% resazurin solution was added to each well. Resazurin is a blue dye which, upon reduction by living cells, turns to a pink resorufin product. Plates were shaken for 1 hour after the addition of the dye. The MIC was recorded as the well with the lowest concentration of test compound where no color change was observed.

The antimicrobial activity of the library of substituted [bis(indol-3yl)]methanes was assessed against a panel of ATCC reference pathogen strains of clinical relevance. Some of the SP-BIM derivatives in this study did not possess any antibacterial activity toward any pathogens used. SP-BIM 1 and SP-BIM 4 displayed antibacterial activity, and only against Gram-positive bacteria (Table 3). The MICs of SP-BIM 1 ranged from an average of 52 μs mL⁻¹ to 250 μg mL⁻¹, whereas SP-BIM 4 had MICs ranging from 104 μg mL⁻¹ to 166 μg mL⁻¹.

TABLE 3 Antibacterial activities of BIM derivatives. MIC (μg/mL) Gram-Positive Bacteria Streptococcus Bacillus Enterococcus Corynebacterium Staphylococcus pyogenes cereus faecium diphtheriae aureus ATCC ATCC ATCC ATCC ATCC Compound 19615 14579 19434 27010 12600 SP-BIM 1 83 83 52 125 >250 SP-BIM 2 >250 >250 >250 >250 >250 SP-BIM 3 >250 >250 >250 >250 >250 SP-BIM 4 104 125 104 166 166 SP-BIM 5 >250 >250 >250 >250 >250 SP-BIM 6 >250 >250 >250 >250 >250 SP-BIM 7 >250 >250 >250 >250 >250 SP-BIM 8 >250 >250 >250 >250 >250 SP-BIM 9 >250 >250 >250 >250 >250 SP-BIM 10 >250 >250 >250 >250 >250 SP-BIM 11 >250 >250 >250 >250 >250 SP-BIM 12 >250 >250 >250 >250 >250 SP-BIM 13 125 125 125 >250 >250 SP-BIM 14 125 125 125 >250 >250 SP-BIM 15 125 125 125 >250 >250 SP-BIM 16 >250 >250 >250 >250 >250 SP-BIM 17 >250 >250 >250 >250 >250 SP-BIM 18 >250 >250 >250 >250 >250 SP-BIM 19 >250 >250 >250 >250 >250 SP-BIM 20 >250 >25 >250 >250 >250 Gram-Negative Bacteria Yeast Klebisella Escherichia Salmonella Pseudomonas Candida pneumoniae coli tvpkimurium aeruginosa albicans ATCC ATCC ATCC ATCC ATCC Compound 49472 35218 14028 27853 22972 SP-BIM 1 >250 >250 250 250 250 SP-BIM 2 >250 >250 250 250 250 SP-BIM 3 >250 >250 250 250 250 SP-BIM 4 >250 >250 250 250 250 SP-BIM 5 >250 >250 250 250 250 SP-BIM 6 >250 >250 250 250 250 SP-BIM 7 >250 >250 250 250 250 SP-BIM 8 >250 >250 250 250 250 SP-BIM 9 >250 >250 250 250 250 SP-BIM 10 >250 >250 250 250 250 SP-BIM 11 >250 >250 250 250 250 SP-BIM 12 >250 >250 250 250 250 SP-BIM 13 >250 >250 250 250 250 SP-BIM 14 >250 >250 250 250 250 SP-BIM 15 >250 >250 250 250 250 SP-BIM 16 >250 >250 250 250 250 SP-BIM 17 >250 >250 250 250 250 SP-BIM 18 >250 >250 250 250 250 SP-BIM 19 >250 >250 250 250 250 SP-BIM 20 >250 >250 250 250 250

Example 3: SP-BIM Derivatives Potentiate a Broad Range of Antibiotics

To assess the antibiotic potentiating capacity of the library of SP-BIMs, a similar broth microdilution assay was performed according to CLSI 2014, with modifications. Respective antibiotics were added to each well in a twofold serial dilution ranging between 250 μg mL⁻¹ and 0.02 μs mL⁻¹. To each well, the SP-BIM to be tested was added to a final concentration of 50 μg mL⁻¹. The SP-BIMs were screened with 12 antibiotics (imipenem, erythromycin, trimethoprim, ciprofloxacin, streptomycin, aztreonam, cefalexin, vancomycin, ampicillin, doxycycline, chloramphenicol, and kanamycin) against Staphylococcus aureus (ATCC BAA 2312), Bacillus cereus (ATCC 11778), Enterococcus faecalis (ATCC 51299), Pseudomonas aeruginosa (ATCC 9027), Enterobacter cloacae (ATCC BAA 1143), Streptococcus pneumoniae, Klebsiella pneumoniae (ATCC BAA 2814), and Escherichia coli (O157:H7 ATCC 35150). The antibiotics represent different chemical classes (imipenem-carbapenem, erythromycin-macrolide, trimethoprim-inhibits folic acid synthesis, ciprofloxacin-fluroquinolone, streptomycin-aminoglycoside, aztreonam-monobactam, cefalexin-cephalosporin, vancomycin-glycopeptide, ampicillin-β-lactam, doxycycline-tetracycline, chloramphenicol-inhibits protein synthesis, and kanamycin-aminoglycoside). SP-BIMs were assessed as potential adjuvants based on their ability to reduce the MIC of the antibiotic against respective pathogen.

Based on the results shown in Tables 4-7, five of the twenty selected SP-BIMs displayed the ability to reduce the concentration of antibiotic needed to kill the respective pathogen. These included:

-   -   3-(di(1H-indol-3-yl)methyl)benzaldehyde (SP-BIM 6): MICs of all         antibiotics except trimethoprim were reduced at least 4-fold for         MRSA and Streptococcus. No potentiating activity was observed         for Gram-negative bacteria.     -   3-(di(1H-indol-3-yl)methyl)phenol (SP-BIM 9): MICs of all         antibiotics except trimethoprim were reduced at least 4-fold for         MRSA and Streptococcus. Potentiating activity was observed for         the Gram-negative E. coli but only for kanamycin (MICs decreased         from 32 μg mL⁻¹ to 8 μg mL⁻¹) and ciprofloxacin (MICs decreased         from 125 μg mL⁻¹ to 8 μg mL⁻¹).     -   4-(di(1H-indol-3-yl)methyl)aniline (SP-BIM 10): MICs of all         antibiotics except trimethoprim were reduced at least 4-fold for         MRSA and Streptococcus. No potentiating activity was observed         for Gram-negative bacteria.     -   5-(di(1H-indol-3-yl)methyl)benzene-1,2,3-triol (SP-BIM 13): MICs         of all antibiotics except trimethoprim were reduced at least         4-fold for MRSA and Streptococcus. No potentiating activity was         observed for Gram-negative bacteria.     -   5-bromo-2-(di(1H-indol-3-yl)methyl)phenol (SP-BIM 15): MICs of         all antibiotics except trimethoprim were reduced at least 4-fold         for MRSA and Streptococcus. No potentiating activity was         observed for Gram-negative bacteria.

TABLE 4 Adjuvant activity of SP-BIMs 1-20 with antibiotics against MRSA. MIC (μg/mL) Treatment Ampicillin Imipenem Cephalexin Erythromycin Aztreonam Trimethoprim No compound >250 4 16 4 >250 250 SP-BIM 1 >250 4 16 4 >250 250 SP-BIM 2 >250 4 16 4 >250 250 SP-BIM 3 >250 4 16 4 >250 250 SP-BIM 4 >250 4 16 4 >250 250 SP-BIM 5 >250 4 16 4 >250 250 SP-BIM 6 0.5 1 2 0.5 >250 ND SP-BIM 7 >250 4 16 4 >250 250 SP-BIM 8 >251 4 16 4 >251 250 SP-BIM 9 0.2 0.2 0.5 4 8 2 SP-BIM 10 0.5 0.2 2 <0.2 63 125 SP-BIM 11 >250 4 16 4 >250 250 SP-BIM 12 >250 4 16 4 >250 250 SP-BIM 13 0.5 0.5 0.5 0.5 16 16 SP-BIM 14 >250 4 16 4 >250 250 SP-BIM 15 0.5 1 2 4 32 125 SP-BIM 16 >250 4 16 4 >250 250 SP-BIM 17 >250 4 16 4 >250 250 SP-BIM 18 >250 4 16 4 >250 250 SP-BIM 19 >250 4 16 4 >250 250 SP-BIM 20 >250 4 16 4 >250 250 MIC (μg/mL) Treatment Streptomycin Ciprofloxacin Vancomycin Doxycycline Kanamycin No compound 63 2 4 8 16 SP-BIM 1 63 2 4 8 16 SP-BIM 2 63 2 4 8 16 SP-BIM 3 63 2 4 8 16 SP-BIM 4 63 2 4 8 16 SP-BIM 5 63 2 4 8 16 SP-BIM 6 1 ND 1 0.2 1 SP-BIM 7 63 2 4 8 16 SP-BIM 8 63 2 4 8 16 SP-BIM 9 1 0.5 0.2 2 1 SP-BIM 10 2 <0.2 2 0.5 0.5 SP-BIM 11 63 2 4 8 16 SP-BIM 12 63 2 4 8 16 SP-BIM 13 1 0.5 0.2 0.2 1 SP-BIM 14 63 2 4 8 1 SP-BIM 15 1 0.2 0.2 0.2 1 SP-BIM 16 63 2 4 8 16 SP-BIM 17 63 2 4 8 16 SP-BIM 18 63 2 4 8 16 SP-BIM 19 63 2 4 8 16 SP-BIM 20 63 2 4 8 16 ND = not determined

TABLE 5 Adjuvant activity of SP-BIMs 1-20 with antibiotics against Streptococcus pneumonia. MIC (μg/mL) Treatment Ampicillin Kanamvcin Cephalexin Erythromycin Aztreonam Trimethoprim Nocompound 0.5 125 250 4 >250 ND SP-BIM1 0.5 125 250 4 >250 ND SP-BIM2 0.5 125 250 4 >250 ND SP-BIM3 0.5 125 250 4 >250 ND SP-BIM4 0.5 125 250 4 >250 ND SP-BIM5 0.5 125 250 4 >250 ND SP-BIM6 <0.2 4 32 0.5 16 ND SP-BIM7 0.5 125 250 4 >250 ND SP-BIM8 0.5 125 250 4 >250 ND SP-BIM9 <0.2 4 64 0.2 16 ND SP-BIM10 <0.2 4 32 0.5 32 ND SP-BIM11 0.5 125 250 4 >250 ND SP-BIM12 0.5 125 250 4 >250 ND SP-BIM13 <0.2 4 16 1 16 ND SP-BIM14 0.5 125 250 4 >250 ND SP-BIM15 <0.2 4 32 1 32 ND SP-BIM16 0.5 125 250 4 >250 ND SP-BIM17 0.5 125 250 4 >250 ND SP-BIM18 0.5 125 250 4 >250 ND SP-BIM19 0.5 125 250 4 >250 ND SP-BIM20 0.5 125 250 4 >250 ND Treatment Streptomycin Ciprofloxacin Vancomvcin Doxycycline Nocompound 16 0.2 1 63 SP-BIM1 16 0.2 1 63 SP-BIM2 16 0.2 1 63 SP-BIM3 16 0.2 1 63 SP-BIM4 16 0.2 1 63 SP-BIM5 16 0.2 1 63 SP-BIM6 2 <0.2 0.5 8 SP-BIM7 16 0.2 1 63 SP-BIM8 16 0.2 1 63 SP-BIM9 1 <0.2 0.2 4 SP-BIM10 2 <0.2 0.5 8 SP-BIM11 16 0.2 1 63 SP-BIM12 16 0.2 1 63 SP-BIM13 1 <0.2 <0.2 4 SP-BIM14 16 0.2 1 63 SP-BIM15 1 <0.2 0.2 8 SP-BIM16 16 0.2 1 63 SP-BIM17 16 0.2 1 63 SP-BIM18 16 0.2 1 63 SP-BIM19 16 0.2 1 63 SP-BIM20 16 0.2 1 63 ND = not determined

TABLE 6 Adjuvant activity of SP-BIMs 1-20 with antibiotics against Escherichia coli. MIC (μg/mL) Treatment Ampicillin Kanamycin Cephalexin Erythromycin Aztreonam Trimethoprim Nocompound 63 32 >250 >250 125 2 SP-BM1 63 32 >250 >250 125 2 SP-BM2 63 32 >250 >250 125 2 SP-BM3 63 32 >250 >250 125 2 SP-BM4 63 32 >250 >250 125 2 SP-BM5 63 32 >250 >250 125 2 SP-BM6 63 32 >250 >250 125 2 SP-BM7 63 32 >250 >250 125 2 SP-BM8 63 32 >250 >250 125 2 SP-BM9 63 8 >250 >250 125 2 SP-BM10 63 32 >250 >250 125 2 SP-BM11 63 32 >250 >250 125 2 SP-BM12 63 32 >250 >250 125 2 SP-BM13 63 32 >250 >250 125 2 SP-BM14 63 32 >250 >250 125 2 SP-BM15 63 32 >250 >250 125 2 SP-BM16 63 32 >250 >250 125 2 SP-BM17 63 32 >250 >250 125 2 SP-BM18 63 32 >250 >250 125 2 SP-BM19 63 32 >250 >250 125 2 SP-BM20 63 32 >250 >250 125 2 Treatment Streptomycin Ciprofloxacin Vancomycin Doxycycline Nocompound 8 125 125 63 SP-BM1 8 125 125 63 SP-BM2 8 125 125 63 SP-BM3 8 125 125 63 SP-BM4 8 125 125 63 SP-BM5 8 125 125 63 SP-BM6 8 125 125 63 SP-BM7 8 125 125 63 SP-BM8 8 125 125 63 SP-BM9 8 8 125 63 SP-BM10 8 125 125 63 SP-BM11 8 125 125 63 SP-BM12 8 125 125 63 SP-BM13 8 125 125 63 SP-BM14 8 125 125 63 SP-BM15 8 125 125 63 SP-BM16 8 125 125 63 SP-BM17 8 125 125 63 SP-BM18 8 125 125 63 SP-BM19 8 125 125 63 SP-BM20 8 125 125 63

TABLE 7 Adjuvant activity of SP-BIMs 1-20 with antibiotics against Klebsiella pneumoniae. MIC (μg/mL) Treatment Ampicillin Imipenem Cephalexin Enthromycin Aztreonam Trimethoprim Nocompound >250 2 8 32 8 16 SP-BIM1 >250 2 8 32 8 16 SP-BLM2 >250 2 8 32 8 16 SP-BIM3 >250 2 8 32 8 16 SP-BIM4 >250 2 8 32 8 16 SP-BIM5 >250 2 8 32 8 16 SP-BIM6 >250 2 8 32 8 16 SP-BIM7 >250 2 8 32 8 16 SP-BIM8 >250 2 8 32 8 16 SP-BIM9 >250 2 8 32 8 16 SP-BIM10 >250 2 8 32 8 16 SP-BIM11 >250 2 8 32 8 16 SP-BIM12 >250 2 8 32 8 16 SP-BIM13 >250 2 8 32 8 16 SP-BIM14 >250 2 8 32 8 16 SP-BIM15 >250 2 8 32 8 16 SP-BIM16 >250 2 8 32 8 16 SP-BIM17 >250 2 8 32 8 16 SP-BIM18 >250 2 8 32 5 16 SP-BIM19 >250 2 8 32 8 16 SP-BIM20 >250 2 8 32 8 16 Treatment Streptomycin Ciprofloxacin Vancomycin Doxycycline Nocompound 32 1 »250 32 SP-BIM1 32 1 »250 32 SP-BLM2 32 1 »250 32 SP-BIM3 32 1 »250 32 SP-BIM4 32 1 »250 32 SP-BIM5 32 1 »250 32 SP-BIM6 32 1 »250 32 SP-BIM7 32 1 »250 32 SP-BIM8 32 1 »250 32 SP-BIM9 32 1 »250 32 SP-BIM10 32 1 »250 32 SP-BIM11 32 1 »250 32 SP-BIM12 32 1 »250 32 SP-BIM13 32 1 »250 32 SP-BIM14 32 1 »250 32 SP-BIM15 32 1 »250 32 SP-BIM16 32 1 »250 32 SP-BIM17 32 1 »250 32 SP-BIM18 32 1 »250 32 SP-BIM19 32 1 »250 32 SP-BIM20 32 1 »250 32

TABLE 8 Adjuvant activity of SP-BIMs 21-29 with antibiotics against MRSA. MIC (μg/mL) Ampicillin Vancomycin Erythromycin Doxycycline Chloramphenicol Kanamycin Ciprofloxacin No Compound 4 2 8 <0.5 <0.5 8 0.5 SP-BIM 21 1 1 8 ND ND 8 0.5 SP-BIM 22 0.5 0.5 8 ND ND 4 0.5 SP-BIM 23 <0.5 <0.5 <0.5 ND ND <0.5 0.5 SP-BIM 24 <0.5 <0.5 <0.5 ND ND 0.5 0.5 SP-BIM 25 0.5 0.5 0.5 ND ND 0.5 0.5 SP-BIM 26 1 0.5 4 ND ND 8 0.5 SP-BIM 27 0.5 0.5 0.5 ND ND 1 0.5 SP-BIM 28 4 1 0.5 ND ND 0.5 0.5 SP-BIM 29 0.5 0.5 8 ND ND 0.5 0.5

TABLE 9 Adjuvant activity of SP-BIMs 21-29 with antibiotics against Bacillus cereus. MIC (μg/mL) Ampicillin Vancomycin Erythromycin Doxycycline Chloramphenicol Kanamycin Ciprofloxacin No Compound >250 4 4 <0.5 4 64 <0.5 SP-BIM 21 250 2 1 <0.5 4 16 <0.5 SP-BIM 22 0.5 2 2 <0.5 4 1 <0.5 SP-BIM 23 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 SP-BIM 24 <0.5 <0.5 <0.5 <0.5 2 <0.5 <0.5 SP-BIM 25 0.5 <0.5 1 <0.5 <0.5 0.5 <0.5 SP-BIM 26 >250 2 2 <0.5 4 8 <0.5 SP-BIM 27 4 2 2 <0.5 4 4 <0.5 SP-BIM 28 250 1 1 <0.5 1 1 <0.5 SP-BIM 29 0.5 1 2 <0.5 4 0.5 <0.5

TABLE 10 Adj uvant activity of SP-BIMs 21 -29 with antibiotics against Enterococcus faecalis. MIC (μg/mL) Ampicillin Vancomycin Erythromycin Doxycycline Chloramphenicol Kanamycin Ciprofloxacin No Compound 2 250 250 0.5 250 250 125 SP-BIM 21 2 250 250 0.5 250 250 64 SP-BIM 22 0.5 125 32 0.5 64 125 2 SP-BIM 23 <0.5 <0.5 <0.5 0.5 <0.5 <0.5 <0.5 SP-BIM 24 <0.5 0.5 0.5 0.5 0.5 0.5 0.5 SP-BIM 25 1 0.5 0.5 0.5 125 0.5 0.5 SP-BIM 26 4 250 250 0.5 250 250 64 SP-BIM 27 1 125 250 0.5 250 250 64 SP-BIM 28 0.5 0.5 0.5 0.5 0.5 0.5 0.5 SP-BIM 29 1 0.5 250 0.5 250 125 1

TABLE 11 Adjuvant activity of SP-BIMs 21-29 with antibiotics against Pseudomonas aeruginosa. MIC (μg/mL) Ampicillin Vancomycin Erythromycin Doxycycline Chloramphenicol Kanamycin Ciprofloxacin No Compound >250 >250 >250 32 250 250 0.5 SP-BIM 21 >250 >250 125 32 250 64 0.5 SP-BIM 22 >250 >250 >250 32 125 250 0.5 SP-BIM 23 >250 >250 >250 16 32 250 0.5 SP-BIM 24 >250 >250 >250 32 250 125 0.5 SP-BIM 25 >250 >250 >250 32 125 250 0.5 SP-BIM 26 >250 >250 >250 16 250 250 0.5 SP-BIM 27 >250 >250 >250 16 250 250 0.5 SP-BIM 28 >250 >250 >250 16 125 125 0.5 SP-BIM 29 >250 >250 >250 16 250 125 0.5

TABLE 12 Adjuvant activity of SP-BIMs 21-29 with antibiotics against Klebsiella pneumonia. MIC (μg/mL) Ampicillin Vancomycin Erythromycin Doxycycline Chloramphenicol Kanamycin Ciprofloxacin No Compound >250 >250 >250 8 >250 >250 250 SP-BIM 21 >250 >250 >250 8 >250 >250 250 SP-BIM 22 >250 >250 >250 8 >250 >250 250 SP-BIM 23 >250 >250 >250 8 >250 >250 250 SP-BIM 24 >250 >250 >250 8 >250 >250 250 SP-BIM 25 >250 >250 >250 8 >250 >250 250 SP-BIM 26 >250 >250 >250 8 >250 >250 250 SP-BIM 27 >250 >250 >250 8 >250 >250 250 SP-BIM 28 >250 >250 >250 8 >250 >250 250 SP-BIM 29 >250 >250 >250 8 >250 >250 250

TABLE 13 Adjuvant activity of SP-BIMs 21-29 with antibiotics against Enterobacter cloacae. MIC (μg/mL) Ampicillin Vancomycin Erythromycin Doxycycline Chloramphenicol Kanamycin Ciprofloxacin No Compound >250 >250 >250 4 16 4 <0.5 SP-BIM 21 >250 125 >250 4 16 2 <0.5 SP-BIM 22 >250 125 >250 4 8 2 <0.5 SP-BIM 23 >250 125 >250 2 8 2 <0.5 SP-BIM 24 >250 125 >250 4 16 2 <0.5 SP-BIM 25 >250 125 >250 8 16 4 <0.5 SP-BIM 26 >250 125 64 4 16 2 <0.5 SP-BIM 27 >250 125 >250 4 16 2 <0.5 SP-BIM 28 >250 125 >250 4 16 2 <0.5 SP-BIM 29 >250 125 >250 4 8 2 <0.5

TABLE 14 Adjuvant activity of SP-BIMs 21-29 with antibiotics against Escherichia coli O157:H7. MIC (μg/mL) Ampicillin Vancomycin Erythromycin Doxycycline Chloramphenicol Kanamycin Ciprofloxacin No Compound 8 250 250 2 8 8 <0.5 SP-BIM 21 8 125 125 1 8 2 <0.5 SP-BIM 22 2 125 250 2 8 4 <0.5 SP-BIM 23 4 250 125 1 4 2 <0.5 SP-BIM 24 4 125 64 2 16 2 <0.5 SP-BIM 25 2 250 250 2 8 4 <0.5 SP-BIM 26 2 16 64 1 8 2 <0.5 SP-BIM 27 2 125 125 2 8 4 <0.5 SP-BIM 28 4 125 250 1 4 1 <0.5 SP-BIM 29 2 125 64 1 8 2 <0.5

The SP-BIMs were screened at 50 μg mL⁻¹ to differentiate the active compounds from those that were less effective. Applicants surprisingly found that the compounds described herein potentiate the antibiotic activities of a range of antibiotic agents. Without wishing to be bound by any particular theory, it is believed that the presence of electron donating groups (those with a lone pair of electrons) (NH₂, OH, CHO, and Br) or NO₂ group in the meta or para positions according to the methyl carbon (C8; as shown in Scheme 3) of the SP-BIM might contribute to adjuvant activity. Another key point is that the oxidation of the methyl carbon (C8) to a methylium moiety causes the molecule to lose activity. Also, it was observed that the addition of a methoxy functional group to C5 (as shown in Scheme 3) of the SP-BIM also did not result in any observed adjuvant effect.

Example 4: SP-BIM 9 and SP BIM 13 Display Potent Antibiotic Adjuvant Activity Against an Extended Range of Pathogens

The antibiotic adjuvant activity of SP-BIM 9 and SP-BIM 13 was further evaluated in an extensive synergy study testing the effect of combining them with antibiotics on seven reference pathogen strains (Bacillus cereus, Streptococcus pyogenes, Enterococcus faecium, Escherichia coli, Klebsiella pneumoniae, and Candida albicans). To assess adjuvant properties of the molecules, a simple checkerboard strategy was used. Concentrations of both agents were systematically diluted to identify concentrations of both drugs that achieve the most potent interaction.

A total of 50 μL of ca-Mueller-Hinton (ca-MHB) broth was distributed into each well of the microdilution plates. The antibiotic was serially diluted along the ordinate (columns) in a twofold serial dilution ranging between 250 μg mL⁻¹ and 0.5 μg mL⁻¹, while the test SP-BIM was diluted along the abscissa (rows) (250 μg mL⁻¹ and 4 μg mL⁻¹). Each microtiter well was then inoculated with 100 μl of bacterial inoculum of 10⁶ CFU/ml in ca-MHB, and the plates were incubated at 35° C. for 24 hours under aerobic conditions. Below is a representation of the test 96-well plates and the respective concentrations used.

The no antibiotic (NA) control was used to determine the MIC of SP-BIM only against the respective pathogen whereas the no SP-BIM (NC) control was used to determine the MIC of antibiotic only against the pathogen. This interaction was quantified using the fractional inhibitory concentration index (FICI) which was calculated using the lowest combination of both antibiotic (A) and SP-BIM (B) that resulted in inhibition of the organism using the following formula (Wright, Trends Microbiol. 2016, 24:862-871):

${FICI} = {\frac{{MIC}\mspace{14mu}{of}\mspace{14mu} A\mspace{14mu}{in}\mspace{14mu}{combination}\mspace{14mu}{with}\mspace{14mu} B}{{MIC}\mspace{14mu}{of}\mspace{14mu} A\mspace{14mu}{only}} + \frac{{MIC}\mspace{14mu}{of}\mspace{14mu} B\mspace{14mu}{in}\mspace{14mu}{combination}\mspace{14mu}{with}\mspace{14mu} A}{{MIC}\mspace{14mu}{of}\mspace{14mu} B\mspace{14mu}{only}}}$

MIC=minimal inhibitory concentration

FICI=fractional inhibitory concentration index

Based on this calculation the interaction effect could be categorized in four classes:

Antagonistic: FICI≥4.0

Indifferent: FICI>1.0-4.0

Additive: FICI>0.5-1.0

Synergy: FICI≤0.5

SP-BIM 9

Tables 15-20 illustrate the results of the FICIs for each antibiotic in combination with SP-BIM 9 against the respective pathogens. Although not displaying any measurable antagonistic activity against any pathogen, SP-BIM 9 demonstrated potent adjuvant activity in combination with most of the antibiotics used in this study (generally good results with all antibiotics except erythromycin and trimethoprim, which gave variable results). Against the Gram-positive pathogens, most of the antibiotics showed high synergy (FICI≤0.5) with SP-BIM 9. Against MRSA, the MICs of all the antibiotics were reduced by at least 4-fold except that of trimethoprim, where an increase in the MIC was observed. The largest reduction in MIC was observed for aztreonam, a monobactam that is not used to treat Gram-positive bacteria because of its ineffectiveness. The MIC of aztreonam only was recorded as 250 μg mL⁻¹ but was reduced to 8 μg mL⁻¹ in combination with 32 μg mL⁻¹ of SP-BIM 9. Against Streptococcus pneumoniae, a similar trend was observed where SP-BIM 9 showed the ability to lower the MIC of the antibiotics at least 4-fold as well. However, no effect was observed with erythromycin. Antibiotic MICs were again reduced for all the antibiotics against Bacillus cereus and Enterococcus faecium except for erythromycin, in which no reduction was observed. Remarkably the Enterococcus faecium strain was highly resistant to vancomycin but the MIC was reduced to susceptible levels with 63 μg mL⁻¹ SP-BIM 9.

SP-BIM 9 was also able to reduce the MICs of the antibiotics against both Gram-negative strains tested (E. coli and K. pneumoniae). However, the effect varied between synergy, additive, and indifferent for the different antibiotics that were tested. Even though the MICs of the antibiotics against the Gram-negative strains were reduced significantly, the reduction required higher levels of SP-BIM 9 for the same antibiotics than against the Gram-positive bacteria. As an example, whilst the concentrations of SP-BIM 9 required to achieve a FICI of ≤0.5 for Gram-positive bacteria ranged between 4 μg mL⁻¹ and 63 μg mL⁻¹, the concentrations required to achieve a similar FICI for E. coli and K. pneumoniae were mostly 125 and 250 μg mL⁻¹.

SP-BIM 13

The FICI results for SP BIM 13 are shown in Tables 21-27. An effect similar to that of SP-BIM 9 was observed against the Gram-positive and Gram-negative pathogens. However, there was generally a considerably greater potentiating effect of SP-BIM 13 on the antibiotics as most MICs were reduced by tenfold or more. Similar to SP-BIM 9, combinations with trimethoprim resulted in an increase in the MIC and hence resulted in an antagonistic effect.

Overall, both SP-BIMs tended to have a greater potentiating effect on the bactericidal antibiotics such as ampicillin, vancomycin, kanamycin, streptomycin, and cephalexin, than on those with bacteriostatic mechanisms of action, including erythromycin and trimethoprim.

TABLE 15 Fractional minimum inhibitory concentrations of antibiotics in combination with SP-BIM 9 against Staphylococcus aureus. Staphylococcus aureus MIC MIC SP- MIC in combination FIC of antibiotic BIM 9 SP- FIC of SP- Σ only only Antibiotic BIM 9 antibiotic BIM 9 FIC Interpretation Erythromycin 0.1 >250 0.05 125.0 0.20 0.50 <0.70 Additive Trimethoprim 1 >250 2.0 4.0 2.00 0.02 <2.02 Indifferent Ciprofloxacin 1 >250 0.5 4.0 0.50 0.02 <0.52 Synergy Streptomycin 8 >250 1.0 63.0 0.13 0.25 <0.38 Synergy Aztreonam >250 >250 8.0 32.0 0.03 0.12 <0.16 Synergy Cefalexin 4 >250 0.5 16.0 0.13 0.06 <0.19 Synergy Vancomycin 2 >250 0.5 4.0 0.25 0.02 <0.27 Synergy Ampicillin 0.5 >250 0.2 125.0 0.40 0.50 <0.90 Additive Doxycycline 8 >250 2.0 32.0 0.25 0.13 <0.38 Synergy Kanamycin 4 >250 1.0 4.0 0.25 0.02 <0.27 Synergy

TABLE 16 Fractional minimum inhibitory concentrations of antibiotics in combination with SP-BIM 9 against Streptococcus pyogenes. Streptococcus pneumonia MIC MIC SP- MIC in combination FIC of antibiotic BIM 9 SP- FIC of SP- Σ only only Antibiotic BIM 9 antibiotic BIM 9 FIC Interpretation Erythromycin >250 >250 >250 >250 1.00 1.00 <2.00 Indifference Trimethoprim 32 >250 8 16 0.25 0.06 <0.31 Synergy Ciprofloxacin 2 >250 0.02 64 0.01 0.26 <0.27 Synergy Streptomycin 32 >250 0.2 16 0.01 0.06 <0.07 Synergy Aztreonam 125 >250 ND ND ND ND <0.00 ND Cefalexin 250 >250 32 125 0.13 0.50 <0.63 Additive Vancomycin 2 >250 0.2 64 0.10 0.26 <0.36 Synergy Ampicillin >250 >250 0.1 16 0.00 0.06 <0.06 Synergy Doxycycline 16 >250 4 125 0.25 0.50 <0.75 Additive Kanamycin 32 >250 4 8 0.13 0.03 <0.16 Synergy ND = not determined

TABLE 17 Fractional minimum inhibitory concentrations of antibiotics in combination with SP-BIM 9 against Bacillus cereus. Bacillus cereus MIC MIC SP- MIC in combination FIC of antibiotic BIM 9 SP- FIC of SP- Σ only only Antibiotic BIM 9 antibiotic BIM 9 FIC Interpretation Erythromycin 16 >250 16 >250 1 1 <2.0 Indifferent Trimethoprim >250 >250 2 16 0.008 0.064 <0.1 Synergy Ciprofloxacin 8 >250 2 16 0.25 0.064 <0.3 Synergy Streptomycin 4 >250 0.5 >250 0.125 1 <1.1 Synergy Aztreonam >250 >250 63 63 0.252 0.252 <0.5 Synergy Cefalexin >250 >250 ND ND ND ND ND ND Vancomycin 2 >250 ND ND ND ND ND ND Ampicillin 8 >250 ND ND ND ND ND ND Doxycycline 4 >250 0.5 125 0.125 0.5 <0.6 Synergy Kanamycin 2 >250 1 8 0.5 0.032 <0.5 Synergy ND = not determined

TABLE 18 Fractional minimum inhibitory concentrations of antibiotics in combination with SP-BIM 9 against Enterococcus faecium. Enterococcus faecium MIC MIC SP- MIC in combination FIC of antibiotic BIM 9 SP- FIC of SP- Σ only only Antibiotic BIM 9 antibiotic BIM 9 FIC Interpretation Erythromycin ND ≥250 ND ND ND ND ND ND Trimethoprim 4 ≥250 ND ND ND ND ND ND Ciprofloxacin 8 ≥250 ND ND ND ND ND ND Streptomycin 32 ≥250 8   16 0.3 0.1 ≤0.3 Synergy Aztreonam 125 ≥250 ND ND ND ND ND ND Cefalexin 250 ≥250 ND ND ND ND ND ND Vancomycin 16 ≥250 0.2 64  0.013 0.3  ≤0.31 Synergy Ampicillin 250 ≥250 0.1 64 0.0 0.3 ≤0.3 Synergy Doxycycline 8 ≥250 ND ND ND ND ND ND Kanamycin 125 ≥250 ND ND ND ND ND ND ND = not determined

TABLE 19 Fractional minimum inhibitory concentrations of antibiotics in combination with SP-BIM 9 against Klebsiella pneumonia. Klebsiella pneumoniae MIC MIC SP- MIC in combination FIC of antibiotic BIM 9 SP- FIC of SP- Σ only only Antibiotic BIM 9 antibiotic BIM 9 FIC Interpretation Erythromycin 250 ≥250 63 125 0.252 0.5 <0.8 Additive Trimethoprim 8 ≥250 8 125 1 0.5 <1.5 Indifferent Ciprofloxacin 2 ≥250 0.5 63 0.25 0.252 <0.5 Synergy Streptomycin 125 ≥250 16 125 0.128 0.5 <0.6 Additive Aztreonam 125 ≥250 1 16 0.008 0.064 <0.1 Synergy Cefalexin 250 ≥250 4 125 0.016 0.5 <0.5 Synergy Vancomycin 125 ≥250 125 250 1 1 <2.0 Indifferent Ampicillin 250 ≥250 2 250 0.008 1 <1.0 Synergy Doxycycline 16 ≥250 4 125 0.25 0.5 <0.8 Additive Kanamycin 4 ≥250 1 250 0.25 1 <1.3 Indifferent

TABLE 20 Fractional minimum inhibitory concentrations of antibiotics in combination with SP-BIM 9 against Escherichia coli. Escherichia coli MIC MIC SP- MIC in combination FIC of antibiotic BIM 9 SP- FIC of SP- Σ only only Antibiotic BIM 9 antibiotic BIM 9 FIC Interpretation Erythromycin 250 ≥250 250 250 1 1 <2.0 Indifferent Trimethoprim 2 ≥250 8 32 4 0.128 <4.1 Antagonistic Ciprofloxacin 2 ≥250 0.5 32 0.25 0.128 <0.4 Synergy Streptomycin 125 ≥250 8 250 0.064 1 <1.1 Indifferent Aztreonam 125 ≥250 32 125 0.256 0.5 <0.8 Synergy Cefalexin 250 ≥250 16 125 0.064 0.5 <0.6 Synergy Vancomycin 125 ≥250 125 250 1 1 <2.0 Indifferent Ampicillin 250 ≥250 4 16 0.016 0.064 <0.1 Synergy Doxycycline 16 ≥250 8 125 0.5 0.5 <1.0 Synergy Kanamycin 32 ≥250 2 8 0.0625 0.032 <0.1 Synergy

TABLE 21 Fractional minimum inhibitory concentrations of antibiotics in combination with SP-BIM 13 against Staphylococcus aureus. Staphylococcus aureus MIC MIC SP- MIC in combination FIC of antibiotic BIM 13 SP- FIC of SP- Σ only only Antibiotic BIM 13 antibiotic BIM 13 FIC Interpretation Erythromycin 0.1 63 0.02 32 0.2 0.5 0.7 Additive Trimethoprim 1 125 4 63 4.0 0.5 4.5 Antagonistic Ciprofloxacin 1 125 0.5 63 0.5 0.5 1.0 Additive Streptomycin 8 125 0.25 32 0.0 0.3 0.3 Synergy Aztreonam >250 125 32 63 0.1 0.5 <0.6 Additive Cefalexin 4 125 0.5 63 0.1 0.5 0.6 Additive Vancomycin 2 125 0.25 32 0.1 0.3 0.4 Synergy Ampicillin 0.5 125 0.5 4 1.0 0.0 1.0 Additive Doxycycline 8 125 1 32 0.1 0.3 0.4 Synergy Kanamycin 4 125 0.25 32 0.1 0.3 0.3 Synergy

TABLE 22 Fractional minimum inhibitory concentrations of antibiotics in combination with SP-BIM 13 against Streptococcus pneumoniae. Streptococcus pneumoniae MIC MIC SP- MIC in combination FIC of antibiotic BIM 13 SP- FIC of SP- Σ only only Antibiotic BIM 13 antibiotic BIM 13 FIC Interpretation Erythromycin ND ND ND ND ND ND ND ND Trimethoprim 32 >250 125 250 3.9 1.0 <4.9 Antagonistic Ciprofloxacin 2 >250 1 125 0.5 0.5 <1.0 Additive Streptomycin 32 >250 1 63 0.0 0.3 <0.3 Synergy Aztreonam 125 >250 8 63 0.1 0.3 <0.3 Synergy Cefalexin 250 >250 2 63 0.0 0.3 <0.3 Synergy Vancomycin 2 125 0.5 8 0.3 0.1 0.3 Synergy Ampicillin 250 >250 2 63 0.0 0.3 <0.3 Synergy Doxycycline 16 >250 1 63 0.1 0.3 <0.3 Synergy Kanamycin 32 >250 0.5 63 0.0 0.3 <0.3 Synergy ND = not determined

TABLE 23 Fractional minimum inhibitory concentrations of antibiotics in combination with SP-BIM 13 against Enterococcus faecium. Enterococcus faecium MIC MIC SP- MIC in combination FIC of antibiotic BIM 13 SP- FIC of SP- Σ only only Antibiotic BIM 13 antibiotic BIM 13 FIC Interpretation Erythromycin ND ND ND ND ND ND ND ND Trimethoprim 4 125 16 125 4.0 1.0 5.0 Antagonistic Ciprofloxacin 8 125 1 63 0.1 0.5 0.6 Additive Streptomycin 32 125 4 63 0.1 0.5 0.6 Additive Aztreonam 125 125 125 125 1.0 1.0 2.0 Indifferent Cefalexin 250 125 8 63 0.0 0.5 0.5 Synergy Vancomycin 16 ≥250 8 125 0.5 0.5 <1.0 Additive Ampicillin 250 ≥250 16 125 0.1 0.5 <0.6 Additive Doxycycline 8 125 1 63 0.1 0.5 0.6 Additive Kanamycin 125 ≥250 4 63 0.0 0.3 <0.3 Synergy ND = not determined

TABLE 24 Fractional minimum inhibitory concentrations of antibiotics in combination with SP-BIM 13 against Bacillus cereus. Bacillus cereus MIC MIC SP- MIC in combination FIC of antibiotic BIM 13 SP- FIC of SP- Σ only only Antibiotic BIM 13 antibiotic BIM 13 FIC Interpretation Erythromycin 16 125 0.05 63 0.01 0.5 0.5 Synergy Trimethoprim 250 125 250 125 1.00 1.0 2.0 Indifferent Ciprofloxacin 0.5 125 0.5 4 1.00 0.0 1.0 Additive Streptomycin 4 >250 0.5 32 0.13 0.1 <0.3 Synergy Aztreonam 250 125 250 63 1.00 0.5 1.5 Indifferent Cefalexin 250 >250 4 32 0.02 0.1 <0.1 Synergy Vancomycin 2 125 0.25 0.05 0.13 0.0 0.1 Synergy Ampicillin 8 125 0.5 32 0.06 0.3 0.3 Synergy Doxycycline 4 125 1 32 0.25 0.3 0.5 Synergy Kanamycin 2 125 0.25 63 0.13 0.5 0.6 Additive

TABLE 25 Fractional minimum inhibitory concentrations of antibiotics in combination with SP-BIM 13 against Klebsiella pneumoniae. Klebsiella pneumoniae MIC MIC SP- MIC in combination FIC of antibiotic BIM 13 SP- FIC of SP- Σ only only Antibiotic BIM 13 antibiotic BIM 13 FIC Interpretation Erythromycin 16 >250 16 250 1.0 1.0 <2.0 Indifferent Trimethoprim 8 >250 16 250 2.0 1.0 <3.0 Indifferent Ciprofloxacin 2 >250 0.5 32 0.3 0.1 <0.4 Synergy Streptomycin 125 >250 32 8 0.3 0.0 <0.3 Synergy Aztreonam 125 >250 8 63 0.1 0.3 <0.3 Synergy Cefalexin 250 >250 63 63 0.3 0.3 <0.5 Synergy Vancomycin 125 >250 125 250 1.0 1.0 <2.0 Indifferent Ampicillin 250 >250 250 63 1.0 0.3 <1.3 Indifferent Doxycycline 16 >250 2 63 0.1 0.3 <0.4 Synergy Kanamycin 4 >250 2 250 0.5 1.0 <1.5 Indifferent

TABLE 26 Fractional minimum inhibitory concentrations of antibiotics in combination with SP-BIM 13 against Escherichia coli. Escherichia coli MIC MIC SP- MIC in combination FIC of antibiotic BIM 13 SP- FIC of SP- Σ only only Antibiotic BIM 13 antibiotic BIM 13 FIC Interpretation Erythromycin 16 >250 16 250 1.0 1.0 <2.0 Indifferent Trimethoprim 2 >250 8 250 4.0 1.0 <5.0 Antagonistic Ciprofloxacin 2 >250 1 32 0.5 0.1 <0.6 Additive Streptomycin 125 >250 4 63 0.0 0.3 <0.3 Synergy Aztreonam 125 >250 125 250 1.0 1.0 <2.0 Indifferent Cefalexin >250 >250 125 63 0.5 0.3 <0.8 Additive Vancomycin 125 >250 125 250 1.0 1.0 <2.0 Indifferent Ampicillin >250 >250 4 125 0.0 0.5 <0.5 Synergy Doxycycline 16 >250 2 63 0.1 0.3 <0.4 Synergy Kanamycin 32 >250 4 32 0.1 0.1 <0.3 Synergy

TABLE 27 Fractional minimum inhibitory concentrations of antibiotics in combination with SP-BIM 13 against Candida albicans. Candida albicans MIC MIC SP- MIC in combination FIC of antibiotic BIM 13 SP- FIC of SP- Σ only only Antibiotic BIM 13 antibiotic BIM 13 FIC Interpretation Erythromycin 16 >250 1 250 0.1 1.0 <1.1 Indifferent Trimethoprim >250 >250 250 250 1.0 1.0 <2.0 Indifferent Ciprofloxacin 63 >250 63 250 1.0 1.0 <2.0 Indifferent Streptomycin >250 >250 16 32 0.1 0.1 <0.2 Synergy Aztreonam >250 >250 250 250 1.0 1.0 <2.0 Indifferent Cefalexin >250 >250 63 125 0.3 0.5 <0.8 Additive Vancomycin 16 >250 8 32 0.5 0.1 <0.6 Additive Ampicillin >250 >250 0.5 125 0.0 0.5 <0.5 Synergy Doxycycline 16 >250 2 125 0.1 0.5 <0.6 Additive Kanamycin 125 >250 4 63 0.0 0.3 <0.3 Synergy

Example 5: SP-BIM 13 Breaks the Antibiotic Resistance in Clinical Strains of MRSA and Enterococcus faecium

SP-BIM 13 was tested against clinical antibiotic resistant isolates of MRSA (n=8) and Enterococcus faecium (n=10) to investigate its ability to break antibiotic resistance. First, the resistance profile for each strain was determined by the Kirby Bauer disc diffusion test outlined in CLSI (2014). After incubating at 35° C. for 24 hours, the zones of clearance were measured and the average value (n=3) was recorded. Each isolate was classified as resistant, intermediate, or susceptible based on the size of zone of inhibition from a particular antibiotic. In this study, only those antibiotics to which the bacterial strain was classified as resistant were evaluated. The checkerboard assay as previously described was used to assess the ability of SP-BIM 13 to reduce the MIC breakpoint of the antibiotic to that susceptibility. Each experiment was performed in duplicate and values are represented as the average FICI.

The average zones of inhibition of MRSA (Table 28) and E. faecium (Table 29) were referenced against the clinical breakpoints for bacteria published by the European Society for Clinical Microbiology and Infections Disease (EUCAST, Version 8.1) (2018) to determine their resistance for each antibiotic (Tables 30 and 31). The strains were then classified as resistant or susceptible accordingly (Tables 32 and 33). SP-BIM 13 was only used with the antibiotics to which the respective strain was resistant.

Table 34 shows the results of the antibiotic resistance breaking capability of SP-BIM 13 against antibiotic resistant strains of MRSA. Without addition of the compound, the MIC of each antibiotic for the respective MRSA strain fell over the resistant breakpoint outlined by EUCAST in 2018. However, SP-BIM 13 reduced the MIC of the antibiotic to below the susceptible breakpoint. Table 34 also shows the corresponding concentration of SP-BIM 13 that was required to break the bacteria's resistance to the antibiotic which ranged from 1 mg mL⁻¹ to 63 μg mL⁻¹. All MRSA strains were resistant to ampicillin (MIC≥250 μg mL⁻¹). However, SP-BIM 13 reduced the MICs for 100-fold in most cases ranging from 4 μg mL⁻¹ to 0.5 μg mL⁻¹. Similarly, the MIC of streptomycin ranged between 63 μg mL⁻¹ to 125 mL⁻¹ but addition of SP-BIM 13 (16 μg mL⁻¹) resulted in a reduction of MIC to 0.5 μg mL⁻¹ to 2 μg mL⁻¹.

The resistance breaking effect of SP-BIM 13 against clinical strains of E. faecium is shown in Table 35. All strains displayed resistance toward Vancomycin, MIC=32 μg mL⁻¹ to 63 μg mL⁻¹, well above the resistant breakpoint of 4 μg mL⁻¹. Addition of SP-BIM 13 reduced the MIC of vancomycin between 0.2 μg mL⁻¹ to 2 μg mL⁻¹. The resistant breaking effect was extended to the other antibiotics used to treat E. faecium.

These results are especially important as MRSA and vancomycin-resistant Enterococcus faecium are listed on the World Health Organization's list of priority bacteria to which new antibiotics are needed.

TABLE 28 Susceptibility profile of MRSA strains. MRSA Zone of clearance (mm) strain Ampicillin Chloramphenicol Ciprofloxacin Streptomycin Erythromycin Kanamycin Doxycycline 1621 11.5 24.5 31.5 17.0 21.5 19.5 21.0 5455 14.5 22.0 29.5 17.0 20.5 19.5 22.5 7698 10.5 16.5 22.5 12.0 17.5 8.5 10.5 10132 14.0 21.5 9.5 8.5 9.0 8.0 12.0 7172 14.5 19.5 26.5 18.5 17.5 20.5 19.0 7153 13.5 18.0 22.5 16.0 18.5 19.5 18.0 5872 9.0 20.5 14.5 8.0 0.0 0.0 15.0 1594 13.0 18.5 26.0 11.5 19.0 11.5 12.5

TABLE 29 Susceptibility profile of Enterococcus faecium strains. E. faecium Zone of clearance (mm) strain Ampicillin Vancomycin Ciprofloxacin Streptomycin 24169 33 10 33 19 21024 32 9 30 17 21955 32 15 35 13 15134 37 12 33 20 RC63 12 8 8 5 23668 39 10 35 13 22870 10 10 12 29 22003 37 16 35 18 23230 36 5 37 14 23227 26 9 37 25

TABLE 30 Antibiotic breakpoints for MRSA strains obtained from EUCAST in 2018. Interpretation of zone diameters (mm) Antibiotic Resistant< Susceptible > Ampicillin 18 18 Chloramphenicol 14 15 Ciprofloxacin 13 14 Streptomycin 13 16 Erythromycin 16 20 Kanamycin 13 18 Doxycycline 19 20

TABLE 31 Antibiotic breakpoints for E. faecium strains obtained from EUCAST in 2018. Interpretation of zone diameters (mm) Antibiotic Resistant < Susceptible > Ampicillin 19 20 Vancomycin 12 13 Ciprofloxacin 15 15 Streptomycin 14 14

TABLE 32 Interpretive standards for MRSA strains. MRSA Strain Ampicillin Chloramphenicol Ciprofloxacin Streptomycin Erythromycin Kanamycin Doxycycline 1621 R S S S S S S 5455 R S S S S S S 7698 R S S R S R R 10132 R S R R R R R 7172 R S S S S S R 7153 R S S I S S R 5872 R S S R R R R 1594 R S S R S R R R = Resistant, S = Susceptible, I = Intermediate

TABLE 33 interpretive standards for E. faecium strains. E. faecium strain Ampicillin Vancomycin Ciprofloxacin Streptomycin 24169 S R S S 21024 S R S S 21955 S S S R 15134 S S S S RC63 R R R R 23668 S R S R 22870 R R R S 22003 S S S S 23230 S R S S 23227 S R S S R = Resistant, S = Susceptible, I = Intermediate

TABLE 34 Reduction of MICs of antibiotics against MRSA to below susceptible breakpoint values by SP-BIM 13. MIC of Rescue MIC of antibiotic in concentration MRSA antibiotic combination of SP-BIM 13 FIC FIC strain Antibiotic only (μg/mL) (μg/mL) antibiotic compound ΣFIC Interpretation 10132 Ampicillin 250 0.5 16 0.002 0.064 <0.07 Synergy Ciprofloxacin 125 0.5 32 0.004 0.128 <0.13 Synergy Streptomycin 63 0.5 16 0.008 0.064 <0.07 Synergy Erythromycin 250 1 32 0.004 0.128 <0.13 Synergy Doxycycline 8 0.5 8 0.063 0.032 <0.09 Synergy 7172 Ampicillin 250 2 32 0.008 0.128 <0.14 Synergy Doxycycline 8 2 32 0.250 0.128 <0.38 Synergy 5872 Ampicillin 250 0.5 32 0.002 0.128 <0.13 Synergy Streptomycin 125 0.5 16 0.004 0.064 <0.07 Synergy Doxycycline 32 4 16 0.125 0.064 <0.19 Synergy Erythromycin 250 4 32 0.016 0.128 <0.14 Synergy 1621 Ampicillin 250 0.5 32 0.002 0.128 <0.13 Synergy 5455 Ampicillin 250 1 63 0.004 0.252 <0.26 Synergy 7698 Ampicillin 250 2 32 0.008 0.128 <0.14 Synergy Streptomycin 125 2 8 0.016 0.032 <0.05 Synergy Doxycycline 16 1 32 0.063 0.128 <0.19 Synergy 7153 Ampicillin 250 0.5 63 0.002 0.252 <0.25 Synergy Streptomycin 63 1 16 0.016 0.064 <0.08 Synergy Doxycycline 8 1 32 0.125 0.128 <0.25 Synergy 1594 Ampicillin 250 4 32 0.016 0.128 <0.14 Synergy Streptomycin 63 8 16 0.127 0.004 <0.13 Synergy Doxycycline 8 1 63 0.125 0.3 <0.43 Synergy

TABLE 35 Fractional minimum inhibitory concentrations of antibiotic resistant strains of clinical strains of resistant Enterococcus faecium treated with ineffective antibiotics and SP-BIM 13. MIC of Rescue MIC of antibiotic in concentration E. faecium antibiotic combination of SP-BIM 13 FIC FIC strain Antibiotic only (μg/mL) (μg/mL) antibiotic compound ΣFIC Interpretation 24169 Vancomycin 63 0.5 32 0.008 0.128 <0.14 Synergy 21024 Vancomycin 63 1 32 0.016 0.128 <0.14 Synergy 21955 Streptomycin 125 0.5 63 0.004 0252 <0.26 Synergy RC63 Ampicillin 250 2 63 0.008 0252 <0.26 Synergy Vancomycin 32 0.2 63 0.006 0252 <0.26 Synergy Streptomycin 125 1 8 0.008 0.032 <0.04 Synergy Ciprofloxacin 32 0.5 32 0.016 0.128 <0.14 Synergy 23668 Vancomycin 32 1 16 0.031 0.064 <0.10 Synergy Streptomycin 63 1 16 0.016 0.064 <0.08 Synergy 22870 Ampicillin 250 2 32 0.008 0.128 <0.14 Synergy Vancomycin 32 2 1 0.063 0.004 <0.07 Synergy Ciprofloxacin 63 1 8 0.016 0.032 <0.05 Synergy 23230 Vancomycin 32 2 16 0.063 0.064 <0.13 Synergy 23227 Vancomycin 32 1 8 0.031 0.032 <0.06 Synergy

TABLE 36 Rescue concentrations of SP-BIM 23 that reactivate chloramphenicol against Pseudomonas aeruginosa. Chloramphenicol vs P. aeruginosa MIC of chloramphenicol 250 μg/mL MIC of SP-BIM 23 >250 μg/mL MIC of chloramphenicol in combination in 4 μg/mL combination with 64 μg/mL SP-BIM 23

TABLE 37 Rescue concentrations of SP-BIM 26 that reactivate vancomycin against Escherichia coli O157:H7. Vancomycin vs. E. coli O157:H7 MIC of vancomycin 250 μg/mL MIC SP-BIM 26 >250 μg/mL MIC of vancomycin in combination with 125 4 μg/mL μg/mL SP-BIM 26

TABLE 38 Rescue concentrations of SP-BIM 27 that reactivate ampicillin against Escherichia coli O157:H7. Ampicillin vs. E. coli O157:H7 MIC of Ampicillin 16 μg/mL MIC of SP-BIM 27 >250 μg/mL MIC of Ampicillin in combination with 125 2 μg/mL μg/mL SP-BIM 27

TABLE 39 Rescue concentrations of SP-BIM 28 that reactivate kanamycin against Escherichia coli O157:H7. Kanamycin vs. E. coli O157:H7 MIC of Kanamycin 8 μg/mL MIC SP-BIM 28 250 μg/mL MIC of Kanamycin in combination with 32 1 μg/mL μg/mL SP-BIM 28

Example 6: SP-BIM 13 was Successfully Used to Treat Mice with MRSA Septicemia Infections

To determine SP-BIM 13's in vivo adjuvant efficacy, its ability to protect mice from both systemic lethal infections and systemic non-lethal infections by MRSA was tested. The MRSA clinical isolate MRSA HS 10132 was used in this trial, as it was determined to be β-hemolytic in vitro, and was highly infectious to mice based on preliminary investigations. MRSA HS10132 was also resistant to ampicillin and resulted in rapid colonization of tissues based on preliminary studies.

Ten-week old female Swiss albino mice (18-20 g) were used in all mice studies. Mice care and handling was performed according to Buerge and Weiss, “Handling and Restraint” in The Laboratory Mouse, Elsevier 2004, and ethical approval was granted by The University of the West Indies, Campus Research Ethics Committee.

For systemic non-lethal infection, overnight cultures of MRSA HS 10132 were washed twice and re-suspended in phosphate buffer saline (PBS). Each mouse received an intra-peritoneal (i.p.) injection of 200 μl of bacterial suspension (1.5×10⁷ CFU mL⁻¹). One hour after infection, the mice were divided into eleven groups (six mice per group) and treated subcutaneously with the respective treatments: T0—Vehicle alone (5% DMSO+5% Polysorbate 20 in PBS); T1—ampicillin (Amp) only (125 mg kg⁻¹); T2—Amp+5 mg kg⁻¹ SP-BIM 13; T3—Amp+10 mg kg⁻¹ SP-BIM 13; T4—Amp+25 mg kg⁻¹ SP-BIM 13; T5—vancomycin (Van) only (125 mg kg⁻¹); T6—Van+5 mg kg⁻¹ SP-BIM 13; T7—Van+10 mg kg⁻¹ SP-BIM 13; T8—Van+25 mg kg⁻¹ SP-BIM 13; T9—5 mg kg⁻¹ SP-BIM 13 only; and T10—10 mg kg⁻¹ SP-BIM 13 only.

The mice were then treated once daily for two subsequent days (i.e., 24 and 48 hours). Twenty-four hours after the last dose, the mice were euthanized and their spleen and liver excised, homogenized in PBS and plated onto mannitol salt agar (MSA) plates. The plates were incubated at 35° C. for 24 hours and then MRSA counts determined (CFU/g organ).

For systemic lethal infection, the mice were treated as in the non-lethal infection studies except that the inoculation dose was 200 μl of 9×10⁹ CFU mL⁻¹ MRSA HS 10132 suspension. The treated mice were then divided into groups for treatment regimens as described for the non-lethal infection studies and treatment was provided once daily for three days following infection. Mortality was monitored daily for five days and moribund mice were euthanized using cervical dislocation. Results are displayed as the percent mice survival (n=6) per day for the 5-day period.

In the non-lethal infection study, SP-BIM 13 was assessed for its potentiating effect on ampicillin to reduce MRSA load in both livers and spleens of the treated animals. FIG. 10A depicts the MRSA load in mice liver after infected mice were subjected to different treatment regimens including untreated (UT), ampicillin only, ampicillin with SP-BIM 13, vancomycin alone, vancomycin with SP-BIM 13, and SP-BIM 13 only. As depicted in FIG. 10A, untreated mice had significantly higher MRSA counts (31000 CFU mL⁻¹) in liver compared to all other treatments. Mice treated with ampicillin only (3500 CFU mL⁻¹) and ampicillin+5 mg kg⁻¹ SP-BIM 13 (7900 CFU mL⁻¹) did not have a significant difference in bacterial load. However, ampicillin+10 mg kg⁻¹ SP-BIM 13 (900 CFU mL⁻¹) and ampicillin+25 mg kg⁻¹ SP-BIM 13 (63 CFU mL⁻¹) almost completely cleared MRSA from the liver. It should be noted that combinations of vancomycin and the three levels of SP-BIM 13 also resulted in almost total clearance of the MRSA from the liver. Treatments with SP-BIM 13 only at the various levels did not result in a significant clearance of the bacteria from the liver.

Similarly, MRSA load in the spleen (FIG. 10B) was significantly lower in mice that received combinations of ampicillin and SP-BIM 13 at 10 mg kg⁻¹ and 25 mg kg⁻¹, when compared to mice that received no treatment, ampicillin only, and ampicillin+5 mg kg⁻¹. Treatment with both levels of SP-BIM 13 only did not significantly reduce MRSA load in the spleen.

In the lethal septicemia studies mice were infected with a lethal dose of MRSA HS10132 and treated as in the non-lethal septicemia study. Mice were monitored for a total of five days post-infection. Percentage of survived animals was plotted against days of treatments. Different treatment regimens include untreated, ampicillin only, ampicillin with SP-BIM 13, vancomycin alone, vancomycin with SP-BIM 13, and SP-BIM 13 only. The survival rate of mice treated with ampicillin in combination with three levels SP-BIM 13 dramatically increased (0% mortality), compared to mice that were untreated and treated with ampicillin only (100% mortality) (FIGS. 11A-B). A similarly high survival rate was observed for mice that were treated with vancomycin only and vancomycin in combination with the three levels of SP-BIM 13. Mice treated with SP-BIM 13 only had lower survival rates but deaths occurred after treatment stopped (40% mortality with 5 mg kg⁻¹, 60% mortality with 10 mg kg⁻¹, and 0% mortality with 25 mg kg⁻¹).

These results show that the potent in vitro antibiotic adjuvant properties displayed by SP-BIM 13 translates in vivo as it can be used with an ineffective antibiotic to protect the mice from systemic infections of MRSA. Even without antibiotics, SP-BIM 13 alone increased survival rate of the infected mice. SP-BIM 13 alone was not able to reduce MRSA counts significantly in the spleen and liver, thus the effect of reducing mortality may be due to a reduction of virulence as was observed in the in vitro studies (reduced biofilm formation and hemolysis of blood as shown below). It must be noted, however, that the mice that survived with treatment by SP-BIM 13 alone were not as active and did not appear to be as healthy as those that received the compound in combination with the antibiotic (data not shown).

Example 7: Screening SP-BIM 9 for its Ability to Reduce Sub-Lethal MRSA Infections in Mice

The ability of SP-BIM 9 to clear MRSA in mice was also evaluated at a sub-lethal level of inoculation.

Mice were inoculated with a sub-lethal dose of MRSA HS10132 as in Example 6. The infected mice were then treated with different combinations of ampicillin (125 mg kg⁻¹) and SP-BIM 9 (5 mg kg⁻¹ and 10 mg kg⁻¹) and the liver and spleen harvested and analyzed for MRSA counts.

The results show that MRSA counts were significantly reduced in liver and spleen of mice treated with combinations of ampicillin and SP-BIM 9 (FIG. 12). The infected mice were subjected to different treatment regimens including untreated (UT), ampicillin only, ampicillin with SP-BIM 9, and SP-BIM 9 only. The liver and spleen of the treated mice were harvested and analyzed for MRSA counts. MRSA load in the spleen of untreated mice (9,300 CFU g⁻¹) and mice treated with ampicillin only (14,622 CFU g⁻¹) were significantly higher than mice treated with combinations of ampicillin and SP-BIM 9 at 5 mg kg⁻¹ and 10 mg kg⁻¹ (288 and 211 CFU g⁻¹, respectively).

However, treatment with SP-BIM 9 only, at both 5 mg kg⁻¹ and 10 mg kg⁻¹, resulted in elevated bacterial loads (7327 CFU g⁻¹ and 5800 CFU g⁻¹, respectively). The same trend was observed for MRSA loads in the liver of infected mice. Animals that were treated with combinations of ampicillin and SP-BIM 9 at 5 mg kg⁻¹ and 10 mg kg⁻¹ had significantly lower MRSA counts (167 CFU g⁻¹ and 189 CFU g⁻¹, respectively) when compared to untreated mice (4238 CFU g⁻¹), ampicillin only (7605 CFU g⁻¹), and those that received SP-BIM 9 only at 5 mg kg⁻¹ (3911 CFU g⁻¹) and 10 mg kg⁻¹ (2861 CFU g⁻¹). These results show that SP-BIM 9 cannot clear MRSA cells from the body of the host as it is not per se an antimicrobial compound. The high levels of bacterial load obtained from mice treated with ampicillin only may be as a result of the stress response of the resistant bacterium toward this antibiotic. The potentiating effect of SP-BIM 9 however, was proven as combinations of ampicillin and SP-BIM 9 resulted in almost total clearance of the bacterium from the host's organs.

Example 8: SP-BIMs can Inhibit Biofilm Formed by Staphylococcus aureus

Biofilm inhibition was determined for 9 SP-BIMs (4 active and 5 inactive) using the crystal violet dye retention assay as outlined by O'Toole, J. Vis. Exp. 2010, 47:2437 in standard 96-well microtiter plates. Each SP-BIM was added in a twofold serial dilution with final concentrations ranging from 250 μg mL⁻¹ to 0.2 μg mL⁻¹. An overnight culture of Staphylococcus aureus was adjusted to a 2.0 McFarland standard (equivalent to 6×10⁸ CFU mL⁻¹) in PBS. Cultures were diluted 1:100 in BHI medium and each well seeded with 100 μL. Untreated wells were seeded with 10% DMSO. Plates were incubated for 24 hours without shaking. After incubation, unbound cells and media were aspirated and wells were washed twice with PBS. To each well, 200 μL of 0.1% crystal violet (CV) solution was added and incubated at room temperature for 15 minutes. Plates were washed twice with excess water and 200 uL of 30% acetic acid was used to solubilize the CV and the solution transferred to clean 96-well plates and absorbance measured at 550 nm. Biofilm formation was expressed as a percentage of the untreated controls. All assays were performed in triplicate.

FIG. 13 shows the percentage of biofilm formation of Staphylococcus aureus cells treated with various SP-BIMs. SP-BIMs that demonstrated antibiotic adjuvant properties (SP-BIMs 6, 9, 13, 15) were compared against some of those that did not (SP-BIMs 2, 3, 5, 11, 18). The biofilm formation at different concentrations of the SP-BIMs was also assessed. There was a significant difference in biofilm inhibition between the SP-BIMs that demonstrated (“active”) and those that did not (“inactive”) demonstrate adjuvant activity. With the active SP-BIMs, the percentage of S. aureus biofilm formations ranged between 6% and 65%, whereas with the inactive SP-BIMs, the formation rate was much higher, between 32% and 121%. All SP-BIMs demonstrated an inverse correlation between the percentage of biofilm formation and the concentration of the SP-BIMs that were used. In other words, the higher the SP-BIM concentration was used, the lower percentage of biofilm was formed.

Biofilms play an important role in the pathogenicity and defense of bacteria. Biofilms essentially are a coherent cluster of bacterial cells embedded in a matrix, which is more tolerant of antimicrobials and host defenses compared with planktonic bacterial cells. The bacteria in these aggregates are physically joined together and they produce an extracellular matrix that contains many different types of extracellular polymeric substances (EPS) including proteins, DNA, and polysaccharides.

The ability of SP-BIMs to reduce biofilm formation along with enhancing antibiotic activity directly is essential to reversing resistance as planktonic cells are easier to kill than cells embedded within a biofilm.

Example 9: SP-BIM 13 Prevents Hemolysis of Sheep Erythrocytes

SP-BIM 13 was further tested in an inhibition assay of hemolysin production. The sheep blood hemolytic assay is a functional assay measuring the release of hemoglobin from erythrocytes due to the hemolytic activity of α-hemolysin (Khodaverdian et al., Antimicrob. Agents Chemother. 2013, 57:3645-3652). Staphylococcus aureus was grown at 37° C. for 24 hours and adjusted to a 2.0 McFarland standard (equivalent to 6×10⁸ CFU mL⁻¹) in PBS. SP-BIM 13 was added in a twofold serial dilution with final concentrations ranging from 250 μg mL⁻¹ to 0.2 μg mL⁻¹ and incubated for 6 h at 37° C. 100 μL of bacterial culture was filtered using a 0.2 μm filter and added to 900 μL hemolysin buffer (0.145 M NaCl, 0.02 M CaCl2) and 25 μL of defibrinated sheep blood. The solution was incubated for 15 minutes at 37° C. Samples were centrifuged (5,500×g, room temperature, 1 minute) to pellet any un-lysed blood cells. Hemolytic activity was determined by measuring the optical density at 541 nm. Sterile culture medium served as the standard for 0% hemolysis, and untreated bacterial culture was designated as the standard for 100% hemolysis. The percentage of hemolysis inhibition was calculated by comparison with the control culture. Assays were performed in triplicate.

SP-BIM 13 was tested for its ability to prevent hemolysin production in Staphylococcus aureus. Bacterial cells were incubated with varying concentrations of the compound and sheep erythrocytes were incubated with the culture supernatants. The results (FIG. 14) demonstrate that SP-BIM 13 inhibits hemolysin production in S. aureus cells. The results also show that concentration of SP-BIM 13 was adversely correlated to the percent red blood cell (RBC) lysis as the higher concentration of SP-BIM 13 resulted in lower lysis. Concentrations as low as 1 ug mL⁻¹ resulted in less than 50% lysis of RBCs.

Example 10: SP-BIM 13 Binds to the Catalytic Domain of Histidine Kinase walK

in silico predictions using Maestro Software (Version 11.7) suggest binding of several SP-BIM 13 to the ATP-binding domain of B. cereus Histidine Kinase (HK) walK (PDB: 3SL2, chain A, residues 451-611). The software predicts that SP-BIM 13 docks in the ATP binding site in a mode similar to that of the natural product ADP. This suggests that SP-BIM 13 may be actively competing with ATP at its binding site on histidine kinase, which then inhibits phosphorylation of the enzyme that is necessary for the stress response of the bacteria.

FIGS. 15A-C shows representative docking poses based on the GLIDE docking scoring function used to assess the in silico molecular docking of the library of SP-BIMs to the CA portion of the enzyme. Among the compounds shown in FIGS. 15A-C, the natural ligand (ADP) had the most favorable ligand binding free energy score, but SP-BIM 9 and 13 had similar binding scores and poses. These were then followed by SP-BIM 2, 17, and 12. The predicted higher binding affinity of SP-BIM 9 and 13 was mirrored in the in vitro studies where these compounds displayed the highest antibiotic potentiating effects.

In some embodiments, the compound disclosed herein is selected from the group consisting of the compounds in Table 40. The SP-BIMs shown below in Table 40 have even more favorable docking scores than those of SP-BIM 9 and SP-IM 13, suggesting these compounds may possess further improved antibiotic adjuvant properties.

FIGS. 19A-B show in silico docking poses of SP-BIMs 33 and 34, respectively.

TABLE 40 Docking scores for SP-BIMs 21-24 and 30-32. SP-BIM Docking Structure Name Number Score

3,3′-((4-bromophenyl)- methylene)bis(1H-indol- 6-ol) 23 −12.273

3,3′-(4-hydroxyphenyl)- methylene)bis(1H-indol- 6-ol) 30  −8.6

5-(bis(6-hydroxy-1H- indol-3-yl)methyl)- benzene-1,2,3-triol 22  −8.457

3,3′-((4-aminophenyl)- methylene)bis(1H-indol- 6-ol) 31  −8.428

3,3′-((4-bromophenyl)- methylene)bis(6-bromo- 1H-indole) 21  −8.331

5-(bis(6-bromo-1H- indol-3-yl)methyl)- benzene-1,2,3-triol 24  −7.703

5-(bis(6-amino-1H-indol- 3-yl)methyl)benzene- 1,2,3-triol 32  −7.321

5-(1,1-di(1H-indol-2-yl)- propyl)benzene-1,2,3- triol 33 −40.73

5-(hydroxydi(1H-indol- 2-yl)methyl)benzene- 1,2,3-triol 34 −47.48

Example 11: SP-BIM 13 Downregulates MRSA Global Regulator Genes Involved in Resistance and Pathogenicity

The HK walK of Gram-positive bacteria is part of a two-component system that regulates prokaryote responses to environmental stress. The second part of this system is the corresponding cognate response regulator. In response to an environmental stimulus, the HK auto-phosphorylates a highly conserved His residue. The His residue is then transferred to an Asp residue on the response regulator molecule, altering its activity.

It has been suggested that the walk-R two component system is, at least in part, responsible for the expression of genes involved in stress responses of the bacteria (Velikova et al., ACS Med. Chem. Lett. 2016, 4:891-894; Zheng et al., J. Nat. Sci. 2015, 1). The expression of the Staphylococcal accessory regulator (sarA) and accessory gene regulator (agr) was examined, which are two global regulator genes in MRSA which are involved in defense and virulence. sarA is a pleiotropic transcriptional regulator of virulence factors that can bind to the promoter regions of a subset of genes that it regulates. In contrast, agr locus plays an essential role in up-regulating exo-protein gene expression, e.g., alpha hemolysin gene (hla) and Staphylococcal enterotoxin-B (seb), while down-regulating the synthesis of cell-surface adhesins during the transition from exponential to post exponential phase (Morrison et al., Front. Cell. Infect. Microbiol. 2012, 2:26).

To assess the effect of SP-BIM 13 on antibiotic resistance and virulence, gene expression analysis was performed on MRSA cells exposed to a sub-lethal concentration of ampicillin. The exposure was used as a stressor on the cells to elicit a response from the bacteria. In brief, actively dividing cells were treated with ampicillin only (125 μg mL⁻¹), ampicillin in combination with SP-BIM 13 at 5 μg mL⁻¹ and 10 μg mL⁻¹, respectively, and SP-BIM 13 only at 5 μg mL⁻¹ and 10 μg mL⁻¹, respectively. Total RNA was extracted two hours after exposure to the compounds and converted to cDNA. Real time gene expression was monitored using the Analytik Jena Qtower and reactions were performed using SYBR® Green JumpStart™ Taq ReadyMix™ (Sigma-Aldrich). The cycling program was carried out as recommended by the manufacturer with an annealing temperature of 60° C. for 35 cycles. Result data was analyzed using the 2-ΔCT method; samples induced with 10% DMSO were used as the control. 16S rRNA gene was used as the reference housekeeping gene to normalize gene expression. cDNA synthesis was performed using the cDNA mastermix (5× All-In-One kit, Bioland) starting with 2 ug of RNA.

The expression of the global regulators sarA, agrA and RNA III genes (FIG. 16A) were upregulated profoundly in cells exposed to ampicillin only. This could be because the bacteria recognized the antibiotic as a threat, and deployed stress response mechanisms to circumvent cell death. The expression of the mecA and blaZ genes, which are responsible for the bacteria's resistance to the antibiotic, was upregulated too (FIG. 16B). The fnbA gene (FIG. 16B) was also upregulated, indicating that exposure to the antibiotic also increased the bacterium's virulence.

Remarkably, the expression of both the downstream and regulator genes were significantly reduced when the cells were exposed to SP-BIM 13 only, or to SP-BIM 13 in combination with ampicillin. This result (FIGS. 16A and 16B) indicated that the compound was effective in controlling MRSA resistance and virulence by blocking the expression of genes responsible for these effects. This effect could be linked back to the compounds' ability to competitively inhibit the walk enzyme and prevent regulation of these genes.

Example 12: Assessment of SP-BIM Toxicity Evaluation of Hemolysis

Hemotoxicity of the SP-BIMs were assessed following Wauford, “Hemolysis Assay”, protocols.io/view/hemolysis-assay-fxkbpkw (2016). Briefly, twofold serial dilutions of each test SP-BIM were added to 2% sheep erythrocyte solution and incubated for 30 minutes at 37° C. Samples were centrifuged at 2500 g for 5 minutes and the absorbance of the supernatants measured at 541 nm. Values were represented as percent hemolysis using freeze thaw cells as 100% lysis.

Even though hemotoxicity is rare, it is a useful parameter to assess the toxicity of a potential xenobiotic. Toxicity was measured by hemoglobin release which is an indication of red blood cell (RBC) lysis. Most SP-BIMs displayed low hemotoxicity even at high concentrations. However, SP-BIMs 6, 11 and 18 proved to be very hemotoxic at concentrations between 125-16 μg mL⁻¹. The other SP-BIMs tested had a maximum hemolysis of only 19% and decreased as compound concentrations decreased to 0.4% (FIG. 17)

In Vitro Cytotoxicity and In Vivo Acute Toxicity of SP-BIM 13 in Mice

In vitro cytotoxicity of SP-BIM 13 was assessed using the MTT assay against with Human Umbilical Vein Endothelial Cells (HUVEC) in 96-well microtiter plates. Each well was seeded with 10,000 HUVECs and SP-BIM 13 was added to each well in a twofold serial dilution ranging from 250 μg mL⁻¹ to 0.1 μg mL⁻¹. The MTT assay involves NAD(P)H-dependent cellular oxidoreductase enzyme that converts the yellow tetrazolium MTT [3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide] into insoluble (E,Z)-5-(4,5-dimethylthiazol-2-yl)-1,3-diphenylformazan (formazan). The formed formazan can be dissolved with DMSO to give a purple color with characteristic absorption at 540 nm. Intensity of purple color is directly proportional to the cell number and thus indicating the cell viability.

The concentration of SP-BIM 13 that resulted in 50% cell death was recorded as the LC₅₀. 750 μM was identified as the LC₅₀ of SP-BIM 13. This represented a relatively safe cytotoxic value.

SP-BIM 13 was further assessed for acute toxicity following guidelines from The Organization for Economic Co-Operation and Development (OECD). Mice were given one subcutaneous injection of SP-BIM 13 at two levels (i—2000 mg/kg and ii—300 mg/kg). The health and mortality of the animals was monitored daily and moribund mice were euthanized by cervical dislocation. Average mice weight and mass of food consumed per day was also measured as indicators of health. Mice injected with vehicle served as the untreated control.

Mice treated with SP-BIM 13 were monitored for 14 days and FIGS. 18A and 18B demonstrate the relative mice weights and mass of food consumed after treatment with SP-BIM 13, respectively. During the observation period there was no deterioration in mice health and as a result no mice deaths were recorded. Both mice weight and appetite did not significantly vary from the untreated mice. This shows that SP-BIM 13 does not adversely affect mice. 

1-104. (canceled)
 105. A method of treating, preventing, or reducing the risk of a microbial infection in a patient, comprising administering to a patient a compound of Formula A or B:

or a pharmaceutical composition thereof; wherein: each occurrence of R₉ is independently selected from the group consisting of NH₂, NO₂, OH, CHO, halogen, and (C₁ to C₆)alkyl optionally substituted with one or more of halogen, OH, NH₂, NO₂, or CHO; and wherein R₉ is substituted on the phenyl ring of Formula A or the imidazole ring of Formula B; m is 0 to 5; each occurrence of R₁₀ is independently H, halogen, OH, CN, NO₂, OCF₃, (C₁ to C₆)alkyl, (C₂ to C₆)alkenyl, (C₂ to C₆)alkynyl, (C₁ to C₆)alkoxy, (C₃ to C₇)cycloalkyl, 3-7-membered heterocycle, (C₁ to C₆)alkylthio, NR_(a)R_(b), (C₁ to C₆)haloalkyl, (CH₂)_(p)(C₃ to C₇)cycloalkyl, (CH₂)_(p)OR_(a), (CH₂)_(p)SR_(a), (CH₂)_(p)NR_(a)R_(b), (CH₂)_(p)(C₁ to C₆)haloalkyl, or CH(indole)₂, in which said heterocycle comprises at least one heteroatom selected from the group consisting of nitrogen, oxygen and sulfur and may be optionally substituted by from one to three groups which may be the same or different selected from the group consisting of halogen, OH, CN, (C₁ to C₄)alkyl, (C₁ to C₄)haloalkyl and (C₁ to C₄)alkoxy, or alternatively two R₁₀ taken together with the ring atoms they are connected to form a 3-7-membered aromatic ring; wherein R₁₀ is a group substituted on the indole ring and/or the phenyl ring of Formula A or on the indole ring and/or the imidazole ring of Formula B; each of n, o, p and q is independently an integer from 0 to 4; R₇ and R₈ are each independently H, halogen, OH, CN, OCF₃, (C₁ to C₆)alkyl, (C₂ to C₆)alkenyl, (C₂ to C₆)alkynyl, (C₁ to C₆)alkoxy, (C₃ to C₇)cycloalkyl, 3-7-membered heterocycle, (C₁ to C₆)alkylthio, NR_(a)R_(b), (C₁ to C₆)haloalkyl, (CH₂)_(p)(C₃ to C₇)cycloalkyl, (CH₂)_(p)OR_(a), (CH₂)_(p)SR_(a), (CH₂)_(p)NR_(a)R_(b), or (CH₂)_(p)(C₁ to C₆)haloalkyl, in which said heterocycle contains at least one heteroatom selected from the group consisting of nitrogen, oxygen, and sulfur and may be optionally substituted by from one to three groups which may be the same or different selected from the group consisting of halogen, OH, CN, (C₁ to C₄)alkyl, (C₁ to C₄)haloalkyl, and (C₁ to C₄)alkoxy; each occurrence of R₁₁ is independently H, halogen, OH, CN, NO₂, OCF₃, (C₁ to C₆) alkyl, (C₂ to C₆)alkenyl, (C₂ to C₆)alkynyl, (C₁ to C₆)alkoxy, (C₃ to C₇)cycloalkyl, 3-7-membered heterocycle, (C₁ to C₆)alkylthio, NR_(a)R_(b), (C₁ to C₆)haloalkyl, (CH₂)_(p)(C₃ to C₇)cycloalkyl, (CH₂)_(p)OR_(a), (CH₂)_(p)SR_(a), or (CH₂)_(p)NR_(a)R_(b), in which said heterocycle comprises at least one heteroatom selected from the group consisting of nitrogen, oxygen and sulfur and may be optionally substituted by from one to three groups which may be the same or different selected from the group consisting of halogen, OH, CN, (C₁ to C₄)alkyl, (C₁ to C₄)haloalkyl and (C₁ to C₄)alkoxy; R_(a) and R_(b) are each independently H, (C₁ to C₆)alkyl, (C₂ to C₆)alkenyl, or (C₃ to C₇)cycloalkyl; and x is absent; or alternatively x is a positive charge and R₁₁ is absent.
 106. The method of claim 105, wherein the pharmaceutical composition further comprises an antimicrobial agent.
 107. The method of claim 106, wherein the activity of the antimicrobial agent is potentiated by the compound.
 108. The method of claim 105, wherein R₇ and R₈ are each independently H, halogen, OH, NR_(a)R_(b), (C₁ to C₆)alkyl, (C₁ to C₆)alkoxy, or (C₃ to C₇)cycloalkyl.
 109. The method of claim 108, wherein R₇ and R₈ are each independently F, Cl, Br, or OCH₃.
 110. The method of claim 105, wherein R₁₁ is H, halogen, OH, or (C₁ to C₆)alkyl.
 111. The method of claim 105, wherein the compound has the structure of Formula A′:


112. The method of claim 105, wherein each occurrence of R₉ is independently selected from the group consisting of halogen, OH, NH₂, NO₂, CHO, and (C₁ to C₆)alkyl optionally substituted with one or more halogen, NH₂, CHO, or OH.
 113. The method of claim 112, wherein each occurrence of R₉ is independently selected from the group consisting of F, Cl, Br, NH₂, NO₂, CHO, CH₃, and C(CH₃)₂.
 114. The method of claim 105, wherein each occurrence of R₁₀ is independently H, halogen, (CH₂)_(p)OR_(a), (CH₂)_(p)NR_(a)R_(b), NO₂, CHO,

(C₁ to C₆)alkyl, or (C₃ to C₇)cycloalkyl, or where two R₁₀ taken together form a 6-membered aromatic ring.
 115. The method of claim 114, wherein each occurrence of R₁₀ is independently selected from the group consisting of F, Cl, Br, CH₃, C(CH₃)₂, N(CH₃)₂, OH, OCH₃, and NH₂.
 116. The method of claim 105, wherein the compound is selected from SP-BIM 1 through SP-BIM 29 as shown in Table
 1. 117. The method of claim 105, wherein the compound is


118. The method of claim 106, wherein the antimicrobial agent is a macrolide, a folic acid synthesis inhibitor, a fluoroquinolone, an aminoglycoside, a monobactam, a cephalosporin, a glycopeptide, a β-lactam, a carbapenem, or a tetracycline.
 119. The method of claim 118, wherein the antimicrobial agent is selected from the group consisting of erythromycin, trimethoprim, ciprofloxacin, streptomycin, aztreonam, cefalexin, vancomycin, ampicillin, doxycycline, and kanamycin.
 120. The method of claim 105, wherein the method further comprises treating, preventing, or reducing the risk of biofilms, hemotoxicity, and/or virulence.
 121. The method of claim 105, wherein the microbial infection is a bacterial infection.
 122. The method of claim 121, wherein the bacterial infection is clinically antibiotic resistant.
 123. The method of claim 121, wherein the bacterial infection comprises Gram-positive bacteria, Gram-negative bacteria, or a mixture thereof.
 124. The method of claim 123, wherein the bacterial infection comprises Bacillus cereus, Streptococcus pyogenes, Streptococcus pneumoniae, Staphylococcus aureus, Enterococcus faecium, Corynebacterium diphtherias, Escherichia coli, Salmonella typhimurium, Pseudomonas aeruginosa, Klebsiella pneumoniae, Candida albicans, or mixtures thereof.
 125. The method of claim 122, wherein the bacterial infection comprises methicillin-resistant Staphylococcus aureus (MRSA).
 126. The method of claim 105, wherein the administration is performed once daily. 